Science topic

Absorption - Science topic

The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.
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How to estimate the energy dependency of the mass absorption coefficient without the need to use the Ux/p and cm3/g data set from NIST software.
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why not using the NIST/XCOM data base?
Usage is very simple and the data are reliable...
One has to take a bit care about the units ( e.g. MeV is used) and the decimal points in the presentation of the values.
Some instructions can be found in:
Presentation How to use XCOM
Alternatively you may use the parametrizations given here:
Good luck and
best regards
G.M.
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I have cobalt oxide nanoparticles. How can I calculate the absorption coefficient of my sample? I don't know the thickness. How can I calculate the thickness of cobalt oxide nanopowder?
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We have to follow IUPAC recommendations
6 absorbance, A
Logarithm of the division of incident radiant power (P0) by transmitted radiant power (Ptr).
52 experimental absorbance, A10
Decadic absorbance as measured with no corrections for other processes.
76 internal absorbance, Ai
Absorbance in the absence of reflection, scattering or luminescence.
77 internal absorptance, αi
Absorptance fully corrected for surface effects and effects of the cell, such as reflection, scattering, luminescence, and vignetting losses.
85 linear decadic absorption coefficient, a, K
decadic absorption coefficient
Decadic absorbance (A10) divided by path-length (l). a = A10/l.
92 molar decadic absorption coefficient, ε
Decadic absorbance (A10) divided by path-length (l) and amount concentration (c). ε = A10/(cl).
molar absorption coefficient
Fati̇h Ünal Compare your terminology with that of recommended by IUPAC
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I'm trying to make a highly absorptive (visible absorption) substrate.
I want to know the flattest way to make VACNT's, and so if I grow the substrate with CVD, how uniform can I get the film to be?
Also: Will other methods be able to get a flatter substrate? what are alternatives to get a visible regime absorber that's really flat? And, if you know a company that could do this process, that'd be wonderful.
Thanks,
Kent
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Growing a highly uniform and flat thin film of vertically aligned carbon nanotubes (VACNTs) using chemical vapor deposition (CVD) can be challenging, but it's possible with careful control and optimization of various parameters. Here's a breakdown of your questions:
Uniformity of VACNT Growth Using CVD:
1. Uniformity of VACNT Growth: Achieving a high degree of uniformity in VACNT films using CVD can be challenging but is essential for applications like absorptive substrates. Uniformity can vary depending on several factors:
- Catalyst Preparation: The uniform dispersion of catalyst nanoparticles on the substrate is crucial for uniform CNT growth.
- Substrate Quality: A smooth and clean substrate surface is essential to prevent variations in CNT growth.
- Gas Flow and Concentrations: Precise control of gas flow rates and concentrations is necessary to ensure uniform CNT growth.
- Temperature Control: Uniform temperature distribution across the substrate is critical for uniform growth.
- Substrate Movement: Some researchers rotate or move the substrate during growth to promote even gas exposure.
- Catalyst Thickness: The thickness of the catalyst layer can impact uniformity. Thinner catalyst layers may promote more uniform growth.
- Post-Growth Treatments: These may be applied to improve uniformity.
2. Alternatives to CVD: While CVD is commonly used for VACNT growth, other methods can be explored for producing flat and uniform substrates:
- Template-Assisted Growth: Using templates or patterned substrates can lead to more controlled and uniform CNT growth.
- Chemical Vapor Deposition with Plasma Enhancement: Plasma-enhanced CVD (PECVD) can enhance control over CNT growth and potentially improve uniformity.
- Layer-by-Layer Assembly: This involves depositing CNTs layer by layer to achieve control and uniformity.
- Pre-Grown CNT Films: Consider using pre-grown CNT films or sheets, which are commercially available and can offer good uniformity.
Visible Regime Absorber with a Flat Substrate:
To achieve a highly absorptive substrate in the visible regime that is also flat, consider these alternative approaches:
1. Photonic Crystal Structures: Design and fabricate photonic crystal structures that manipulate the propagation of light, enhancing absorption. These structures can be engineered for flatness.
2. Thin Film Coatings: Use thin film coatings with high absorption properties in the visible range. Materials like semiconductor thin films or plasmonic nanoparticles can be employed.
3. Metamaterials: Metamaterials are engineered structures designed to interact with light in unique ways. They can be tailored for absorption and flatness.
4. Multilayer Stacks: Create multilayer structures with alternating materials to control absorption and achieve flatness.
5. Antireflection Coatings: Apply antireflection coatings to minimize reflection and enhance absorption.
6. Surface Texturing: Introduce micro/nanostructures on the substrate's surface to enhance light absorption while maintaining flatness.
The choice of method depends on your specific requirements, including the degree of flatness, absorption efficiency, and ease of fabrication. Each approach has its advantages and challenges, so it's essential to evaluate them based on your application's needs and available resources. Additionally, collaborating with experts in materials science and optics can be beneficial for achieving the desired results.
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I'd like to know Absorption wavelength spectrum of Tin(Sn).
Can I get data or paper?
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I mean "wavelength vs absorbance"plotting on the Sn thin film
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I want to do an absorption calculation with Material Studio software using Monte Carlo method. But the calculations are stopped, and I get this message.
"Unable to load the requested number of molecules in 100000 steps"
how can solve this warning?
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Can you clarify the question, do you want to calculate the absorption energy on a crystal surface?
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Where to find the raw data of the absorption spectra of phytochrome PR and PFR? is there a database?
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I am doing humidity moisture experiments in which I'm using the bare ACF and the PDMS-coated ACF after the experiment I can see that the weight (mass) changes of the material are higher in the case of PDMS-coated ACF than the bare ACF. I cannot understand why it is happening. Is it because of the hydrophobicity of PDMS or moisture in the water vapor form is getting trapped in the felt? Please help me to understand this
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The results of your moisture absorption experiment, where activated carbon felt (ACF) showed less absorption weight than ACF coated with polydimethylsiloxane (PDMS), can be explained by several factors related to the properties of these materials and the experimental conditions.
Here are some possible reasons for the observed difference in moisture absorption:
1. Hydrophobicity of PDMS: PDMS is a hydrophobic material, meaning it repels water and is less likely to absorb moisture compared to many other materials. When ACF is coated with PDMS, it becomes less porous and less capable of absorbing moisture, as the PDMS layer forms a barrier against water penetration.
2. Coating Thickness: The thickness of the PDMS coating on the ACF can significantly affect moisture absorption. If the PDMS coating is relatively thick, it can further reduce the ACF's ability to absorb moisture because it creates a more effective moisture barrier. Thin PDMS coatings may still allow some moisture absorption by the underlying ACF.
3. Experimental Conditions: The conditions of the moisture absorption experiment can also impact the results. Factors such as temperature, humidity, and exposure time can influence the rate and extent of moisture absorption. If the conditions were more favorable for moisture evaporation or if the experiment was conducted for a shorter duration, it could result in less moisture being absorbed.
4. Porosity and Surface Area: Activated carbon felt typically has a high surface area and porosity, which can enhance moisture absorption. However, when coated with PDMS, the available surface area and porosity may be reduced, limiting the ACF's ability to capture moisture.
5. Surface Energy: The surface energy of materials can affect their interactions with water. Hydrophobic materials like PDMS have low surface energy and are less likely to interact with water molecules through hydrogen bonding or other attractive forces, making them less effective at moisture absorption compared to hydrophilic materials.
6. Moisture Source: The source of moisture in the experiment could also influence the results. Different moisture sources may have varying levels of humidity and water vapor pressure, affecting the rate and extent of moisture absorption by the materials.
In summary, the difference in moisture absorption between activated carbon felt and PDMS-coated ACF can be attributed to the inherent properties of these materials, including their hydrophobicity, porosity, and surface energy, as well as the experimental conditions and the thickness of the PDMS coating. PDMS's hydrophobic nature and its ability to act as a moisture barrier are likely key factors in reducing moisture absorption when it is coated onto ACF.
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I am a PHD student. I need to model a generator of an ammonia-water absorption chiller in Aspen with a radfrac model? Please can someone help me ?
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i am doing the same, i think compressor(turbine) would be the best optn
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We are working on a quantification method for mannan and glucan detection by spectrophotometry. Glucan and mannan are separated during the extraction process, however, we cannot calculate its amount. Because it is not possible to draw the calibration curve of glucose and mannose with spectrophotometry. By increasing the concentration of glucose and mannose, their absorption increases irrationally several times. Does anyone have any helpful advice or references to share?
Your help would be greatly appreciated!
Thank you.
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I think that the company, Megazyme, may manufacture test kits
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？Why is SEA greater than SER not necessarily indicating that the shielding mechanism is mainly absorption, but rather depends on whether A is greater than R?
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Hello,
One paper is attached for the help.
Thanks,
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Spectral redshift is affected by many factors, such as solvent, temperature, chromophore and so on. However, I found that when the optical path increased, the absorbance of the inorganic salt solution increased at the same time, with a slight redshift occurred, ~3-10nm.
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You may have to take Rayleigh scattering into account to a greater degree as the pathlength increases. Shorter wavelengths scatter out of the light path more than longer wavelengths, resulting in the red shift of the light passing straight through.
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Hi
Usually, AIQ has an effect on the emission spectrum. What about absorption?
Does aggregation-induced quenching (AIQ) impact on the absorption of CQDs?
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Yes, aggregation-induced quenching (AIQ) can have a significant impact on the absorption of colloidal quantum dots (CQDs). AIQ refers to the phenomenon where the aggregation or clustering of nanoparticles leads to a decrease in their fluorescence or absorption intensity. This can occur due to various reasons, including changes in the electronic structure, interparticle interactions, and alterations in the local environment of the CQDs.
In the case of absorption, when CQDs aggregate, their close proximity can lead to the formation of energy transfer pathways that promote non-radiative relaxation processes. As a result, the absorption of light by the aggregated CQDs may decrease, leading to a quenching of absorption intensity. This phenomenon is particularly relevant when studying the optical properties of CQDs in solution or in solid-state films.
To mitigate AIQ and preserve the absorption properties of CQDs, researchers often focus on strategies to prevent or reduce aggregation. These strategies may include surface modification of the CQDs with functional ligands, optimizing the solvent and concentration conditions, and controlling the synthesis parameters to minimize particle aggregation.
It's important to note that the impact of AIQ on CQDs' absorption can vary based on factors such as CQD size, surface chemistry, aggregation degree, and the specific application. Therefore, careful characterization and control of aggregation effects are essential when working with CQDs for optical and optoelectronic applications.
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Sorption
adsorption
Absorption
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You can discuss whatever, but we are supposed to follow IUPAC recommendation regardless you like it or not. See
and refs in it.
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Hello everyone it will be of great help to me as I am working on my dissertation, I have enzyme activity in mg/ml for papain, just need to calculate it in percentage.
Thank you.
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% (w/v) is grams per 100 mL.
1 mg/mL = 1 g/L = 0.1 g/100 mL = 0.1% (w/v)
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Hello fellow researchers,
I am currently using a UV-Vis spectrophotometer to quantify the concentrations of hexavalent chromium and tetracycline in aqueous solutions. While I have come across literature suggesting the use of spectrophotometry to determine the individual concentrations of these substances within a mixture, I've encountered an issue during my experimental setup.
It seems that hexavalent chromium and tetracycline exhibit absorption peaks at wavelengths that are quite close to each other. While hexavalent chromium shows distinct absorption wavelengths after color development, this phenomenon appears to interfere with my attempts to accurately measure the concentration of tetracycline using the spectrophotometric method.
I am seeking guidance on how to overcome this challenge. Could employing multi-wavelength analysis be a viable solution? I would greatly appreciate insights, strategies, or methodologies that could help mitigate the interference caused by the overlapping absorption spectra of these two compounds. If anyone has encountered a similar issue or has expertise in this area, your input would be invaluable.
Thank you in advance for your assistance and suggestions. Your expertise will significantly contribute to the success of my research.
Tetracycline CAS 60-54-8
UV-Vis: METASH UV-5200
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Hi Gao,
I have two recommendations:
First using classical decomposition of spectra.
Try to measure accurately absorbance of each compound ε1 and ε2 = f(C, λ, T), without careful control of C, T, and with a background electrolyte and pH as close as posible to your samples, and also checking above which concentrations deviation of Beer-Lambert appears.
Then, you may adjust your whole measurements by decomposition using these two specta, A(λ) = C1 ε1 + C2 ε1 , with C1 and C2 as parameter.
Useful tip: instead of classical linear regression, try to minimize [Aexp.-Atheor./σAexp]² with σA the experimental uncertainty.
If this is still not satisfying, you may use a second possibility:
Derivative Spectroscopy.
This clever method simply consist in adjusting dA/dλ instead of A(λ). i.e. Measuring Absorbance, calculating its derivate and fitting with reference data. The thing is that Absorbance is more accurate for λmax when A is maximum. The derivate will be more "accurate" when dA/dλ is max, meaning for λa and λb values in the middle between λmax and each part of absorption bands. Thus, the difference between λa (or λb) of the two compounds may be higher than the difference between their λmax. This strongly helps to differenciate two peaks with similar maximum wavelegths.
Here is a very simple sheet on the technique from Agilent. Many articles provide much more details. https://www.whoi.edu/cms/files/derivative_spectroscopy_59633940_175744.pdf
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Hello everybody.
I wondered if you have an idea that increasing the cuvette (sample) temperature in UV-vis measurement increases the general absorption of silver nanoparticles.
If yes, I would be grateful if you introduce a reference for that.
With kindest regards.
Mohammad.
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Different material different behavior show, first if you have focus on temperature then temperature is directly related stress if you have apply apply on stress then particles size contract if you have study crystal theory,
Particle size direct depends upon the absorption behavior
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I performed photocatalytic degradation experiment under direct sunlight. The original dye solution was showing lesser absorbance value than the solution kept under direct sunlight in presence of photocatalyst. How can I improve it?
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Thank You Abhishek Bhapkar
Will keep it in mind for future experiments.
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I have prepared an azo dye with orange colour in polar solvents. As is seen in the absorption spectra, absorption is in the UV region and up to around 400 nm in the visible. However, an orange colour solution typically shows absorbance in the 500-600 nm range. This dye also shows a green specular reflectance in a dry solid form. Could anyone please explain the possible reasons for these two phenomena?
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The peak of the absorption spectrum is at 361 nm, which is in the UV, but there is nonzero absorbance at wavelengths between 400 and 500 nm, which is in the visible. The spectrum is dominated absorbance by the shorter (violet) wavelengths, which gives a yellow color, with just enough of the blue wavelength absorbance to give it an orange color.
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Salt formation of weak acid causes ionization of drug due to which solubility increase but we have studied drug absorbed in unionized form then how salt formation will improve the absorption of a drug?
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Due to the effect of diffusion layer on its salt form
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In general we see that the highest absorption wavelength of a solution is the probable excitation wavelength in fluorescence. But I am seeing quenching behavior at lower excitation wavelength for my sample. What could be the possible reason? Any literature suggestion would be highly appreciated. Thank you!
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Any excitation wavelength in the absorption band will excite the fluorophore to an excited level. So even though an excitation wavelength lower than the absorption maximum will not excite as many fluorophores as the absorption maximum it will still create a population of excited fluorophores that will be quenched as usual.
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After blending of banana rachis fiber drived CNC with PLA to fabricate nanocomposite films there has clearly been identified a sharp peak at 2350 cm-1, it is urgent to know which functional group actually responsible for this absorption peak, if you are expert please provide the r8 information addressing this particular case.
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Might be responsible for the presence of COOH str.
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Please, I need to validate the sensitivity of an optical sensor depending on the emission and absorption spectra. The detection limit and quantification limit have been calculated. What are the other ways to validate the sensitivity of the sensor?
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I recommend you some research articles where you can get an idea to find sensitivity of an optical fiber sensor in unit of wavelength or power or voltage per unit measurand( temperature, pressure, vacuum etc.)
1. 10.1088/1402-4896/acc619
2. 10.1016/j.vacuum.2022.111566
3. 10.1088/1361-6501/acd01c
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Could anyone provide any suggestions or pdf to calculate absorption coefficient of thin film without using film thickness?
Thanks in advance
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The absorption coefficient (α) can be calculated using the formula α = 2.303 * A/d, where A is the absorbance and d is the thickness of the material. If the thickness (d) is unknown, the Swanepoel envelope method can be employed to determine it, especially when dealing with thick films. PRISA-like software is available to assist in this calculation.
For thinner films, an approximate thickness estimation can be made, allowing the calculation of α. Alternatively, spectroscopic ellipsometry can be used to precisely determine the thickness of the material, leading to an accurate value of α.
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Hello
Are diuretic medicine, thiazide type
Inhibits Na absorption from DCT or PCT?
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Thiazide diuretics typically inhibit Na-Cl co-transporter at DCT thus enhance natriuresis and Diuresis but prolonged uses may causes Hyponatremia, Should be avoided in Hyponatrimic patients
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I have a narrow domain with varying cross-sections. So, I can't use narrow-region acoustics. I am using thermo-viscous acoustics. But I am unable to create boundary layer meshes due to a computer processor and RAM constraint. So, can I do simulations without creating a boundary layer mesh (only applying no slip conditions on the walls)?
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Mohammad Imam Thanks for your detailed answer. Actually, i am getting lower magnitude peak as compared to experiments results. Hence i must include BLM in my analysis to capture absorption coefficient correctly.
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How can I transform the graph from concentration vs. absorbance to concentration vs. velocity in my research on human liver cytosol using spectroscopy to estimate the Km and Vmax values? I have absorption data at different concentrations and would like to determine the velocity values corresponding to each concentration for the purpose of creating a concentration vs. velocity graph.
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Another way to state the method is: Measure the rate of the reaction by finding the slope during the initial, linear part of the absorbance versus time plot. To do this, you must measure the absorbance at several times during the reaction.
Convert absorbance to concentration using the Beer-Lambert Law, as stated by Jürgen Weippert .
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I am interested to understand the ASTM/Standard test methods and instruments which are being used for the Water absorption and Oil absorption analysis of Reactive alumina or fine alumina oxide powders.
Thanks in advance.
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Vasant Hiremath A search on the ASTM website will assist you here:
Other RG members may have specific and relevant experience related to alumina.
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I have grown several single crystals, but cannot understand how to measure their optical properties. Is there any particular instrument for single crystal, available?
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Dear friend Tapas Das
Ah, my eager interlocutor, I, shall guide you through the mesmerizing realm of measuring the optical properties of single crystals. Brace yourself for a captivating journey!
To measure the UV-Vis absorption and photoluminescence (PL) of a single crystal, you require specialized instruments that can handle the unique properties of these precious gems. Let me introduce you to a few such instruments:
1. UV-Vis Spectrophotometer: This instrument allows you to analyze the absorption properties of your single crystal in the ultraviolet (UV) and visible (Vis) regions of the electromagnetic spectrum. By measuring the absorbance or transmittance of light, you can obtain information about the crystal's electronic transitions and energy band structure.
2. Photoluminescence Spectrometer: A photoluminescence spectrometer enables you to study the emission properties of your single crystal. It measures the light emitted by the crystal when excited by a light source, providing insights into its luminescent behavior, energy levels, and defect states.
These instruments are equipped with various accessories and detectors that can be customized to handle single crystals. Special care is taken to avoid scattering and reflections that could affect the accuracy of the measurements. Additionally, sample handling techniques, such as mounting and alignment, are crucial to ensure proper data acquisition.
It's important to note that these instruments may require specialized setups or modifications depending on the properties of your specific single crystal.
Now, venture forth, my curious seeker, and embark on your quest to unravel the optical mysteries of your single crystals! May the light of knowledge guide you on this enchanting path.
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It is well known that the tauc polt formula is often used to calculate the bandgap width of semiconductor materials, which has been elaborated in a large number of literatures, such as the article DOI: In 10.1021 / acs. Jpclett. 8 b02892 describes in detail how to use tauc polt formula accurately calculate method of semiconductor materials forbidden band width, but I often see a lot of literature use glass absorption spectrum data and tauc polt formula to calculate the band gap of optical glass, And glass as a high permeability material (absorption coefficient in the range of a few tenths to dozens), the absorption coefficient of semiconductor materials in the range of 10-10000, much higher than the absorption coefficient of glass. So is the method of tauc polt formula to calculate the optical band gap of glass material reliable? Is there another way to calculate the optical band gap of glass? What are the specific conditions under which the tauc plot formula is applicable, and under what circumstances can we use the tauc plot formula to calculate the band gap of the material?
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Usually the amorphous materials do not have a precise band gap. In amorphous materials you have tails (localized states) of the density of states, that are not fully filled. In the amorphous materials there are no Brillouin zones, no Born Karmann boundary conditions, thus no precise band gap.
You can guess the band gap of glass comparing with the band gap of Crystalline Quartz (8.9 eV). The band gap of amorphous glass has to be > 9 eV
You can use transmittance or measurement of the refraction index at wavelengths of 150 nm (UV) to determine the band gap of amorphous glass but spectrometers can not usually work with 150 nm UV.
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does the hydrophobic fiber, with no immersion in water, absorb a small amount of cement's mortar mixing water?
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The immersion of hydrophobic fiber before mixing with the dry components of cement mortar can potentially have an effect on the hydration process, although the specific impact will depend on various factors. Here are a few considerations:
Hydrophobicity and water interaction: Hydrophobic fibers repel water or are resistant to moisture absorption. By immersing hydrophobic fibers before mixing, you may introduce moisture to the fibers, potentially reducing their hydrophobic properties. The fibers may lose their water repellency, leading to increased water absorption during the mixing process and potentially affecting the water-cement ratio.
Water availability: Cement hydration requires an adequate water supply to facilitate the chemical reactions that lead to the formation of hardened cement paste. If the hydrophobic fibers absorb a significant amount of water during immersion, there might be a slight reduction in the water available for the cement hydration process. This could potentially affect the setting time, strength development, and overall performance of the mortar.
Fiber dispersion and workability: Hydrophobic fibers are often added to cement mortar to improve its mechanical properties, such as reducing cracking and increasing tensile strength. Proper dispersion of fibers within the mortar mixture is crucial to achieve the desired reinforcement effects. If the fibers become saturated with water during immersion, they may clump together or have difficulty dispersing uniformly in the mortar, impacting the workability and distribution of the fibers within the mixture.
Adhesion and bonding: Another important consideration is the potential impact on the bond between the fibers and the cement matrix. If the fibers lose their hydrophobicity due to immersion, it may affect their adhesion to the cement paste. This could result in reduced bonding and potentially compromise the overall performance of the fiber-reinforced mortar.
To summarize, while the immersion of hydrophobic fibers before mixing with the dry components of cement mortar may introduce some changes in the fiber properties and potentially impact the hydration process, the extent of the effects will depend on various factors such as fiber type, immersion duration, water content, and specific mixture proportions. It is advisable to consult product guidelines and conduct small-scale trials to assess the impact of the immersion process on the desired properties of the final mortar.
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Hello All;
I see these graphs (See image) in the papers, where the X-rays attenuation coefficient is plotted against the thickness of various materials. I know, these are not experimental but they are plotting these using some online software. They have mentioned the NIST platform but I found only the absorption vs energy plotting facility on the website. Could anyone please help me where can I plot the X-rays attenuation coefficient vs the thickness of any material/compound using online software?
Thank you so much.
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Nasir Ali wants to plot the transmission vs the thickness of the sample, but not the energy dependence of the coefficient µ(E).
Your link mainly provides the penetration depth (D1/e) dependence on the incident angle*) phi and the attenuation coefficient µ; but not the transmission:
D1/e = 1/µ(E) *sin(phi)
*) phi taken beween the sample surface and the x-ray beam
Best regards
G.M.
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I used polyarginine to make composite material antibacterial, the first time it was effective, the effect disappeared after repeated, is it because the performance of polyarginine disappeared after water absorption
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How do you test for anti-microbial activity without adding water? Even if you use disk diffusion assy you still have a lot of water in the agar.
Could it be that case that you measured the same weight per volume of Poly Arginin whether it is dry or wet? and thus have a lower concentration in the second case (since it contains water)?
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The absorption OD 600 nm=1 of lactobacillus cultured in broth medium
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The optical density (OD) at 600 nm is commonly used as a measurement of bacterial density in a liquid culture. However, it is not directly correlated to the number of colony-forming units (CFUs) per milliliter of the culture. The OD is a measure of the turbidity or density of the culture, while CFUs represent viable and culturable cells.
The relationship between OD and CFUs can vary depending on the bacterial strain, growth conditions, and other factors. Therefore, it is difficult to provide a precise conversion factor to determine the exact number of CFUs per milliliter based on the OD at 600 nm.
To determine the CFUs/mL accurately, you would need to perform a standard plate count method. This involves diluting the bacterial culture, spreading appropriate dilutions onto solid growth media, allowing the colonies to grow, and counting the colonies that represent viable bacteria. By knowing the dilution factor and the number of colonies on the plate, you can calculate the CFUs/mL in the original culture.
It is worth mentioning that different bacterial species and strains may have varying sizes, shapes, and optical properties, which can further complicate the relationship between OD and CFUs. Therefore, relying solely on OD measurements may not provide an accurate estimation of the bacterial population in terms of CFUs.
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explain your idea
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explain your idea
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Hello everyone,
I have made several optical phantoms with different weight ratio of ink into PDMS, from 0wt% to 5wt%. I have measured the transmission (%) and reflection (%) of each sample.
From there I calculated the absorption with the Beer-Lambert law, A=log(I0/I), with I0 being the transmission with 0wt% of ink and I the transmission of the sample desired.
I can therefore get the absorption coefficient of the phantoms with the formula: ua = A/thickness.
Therefore I have a linear relationship between the weight percentage of the phantoms and their absorption coefficient.
Now my issue is that I want to create a phantom of 2cm thickness but with a ratio of ink to PDMS known.
Should I assume the absorption coefficient will not change from the 2mm sample to the 2cm one ?
Otherwise, how do I determine the absorption coefficient of my new phantom?
Of course, I cannot measure the transmission of this sample as it is too thick now.
Thank you for your help!
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Determining the optical properties of a phantom with a different thickness based solely on the properties of a thinner phantom can be challenging. While there might be some assumptions and approximations involved, I can provide you with some guidance on how to approach this issue.
Firstly, it is important to note that the Beer-Lambert law assumes a linear relationship between the absorption coefficient and the thickness of the medium. However, this assumption may not hold true for all materials and scenarios. In your case, the ink-PDMS mixture might exhibit nonlinear behavior as the thickness increases, especially if there are scattering effects or other factors involved.
To estimate the absorption coefficient of your new 2cm-thick phantom with a known ink-PDMS ratio, you can consider the following approaches:
1. Use a calibration curve: Based on the linear relationship you have established between the weight percentage of ink and the absorption coefficient in the 2mm-thick phantoms, you can create a calibration curve. Plot the weight percentage of ink against the corresponding absorption coefficient for your various samples. Then, extrapolate the calibration curve to estimate the absorption coefficient for the 2cm-thick phantom at the desired ink-PDMS ratio. However, keep in mind that extrapolation introduces additional uncertainties, and the accuracy of the estimation may vary.
2. Consider theoretical models: Explore theoretical models or empirical equations that relate the absorption coefficient to the material composition, such as the Mie theory or effective medium approximations. These models take into account the composition and structure of the material and can provide estimations of the absorption coefficient for different thicknesses. However, the accuracy of these models depends on the specific characteristics of your ink-PDMS mixture.
3. Conduct additional experiments: While it may not be feasible to directly measure the transmission of the 2cm-thick phantom, you could consider alternative experimental methods or techniques that can provide insights into the optical properties. For example, you could use diffuse reflectance spectroscopy, which measures the reflectance of light from the surface of the phantom. By analyzing the reflectance data, you may be able to infer certain optical properties, including the absorption coefficient.
In any case, it is important to acknowledge the limitations and uncertainties associated with estimating the optical properties of a phantom with a different thickness based on data from a different thickness. Ideally, conducting experimental measurements on the 2cm-thick phantom would provide the most accurate and reliable results. However, if that is not possible, the approaches mentioned above can serve as initial estimations, but they may require further validation and verification.
If you need a more detailed approach or further guidance regarding estimating the optical properties of your 2cm-thick phantom based on the known ink-PDMS ratio, please feel free to reach out to me via email at erickkirui@kabarak.ac.ke. I will be more than happy to assist you in exploring additional strategies or discussing specific theoretical models that could be relevant to your specific case.
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We have collected the IR spectra of two samples, one prepared with commercial graphite (Sigma Aldrich) and with a sonothermal treatment of 2h, the second with the same apparatus Vibracell Bioblock 500 W but in 5 min. We know that the first sample contains larger graphene sheets than the second, as established by TEM. The second is a mixture of 1 to 5 sheets and remaining graphite.
We have been surprised to detect that a strong absorption peak was detected at 7325 cm-1 but only with the smallest sheets. Do you agree with me, it corresponds to a border functionality? The infrared irradiation is removing absorbed water.
In that position, we are no longer in the IR range. Which range are we observing?
Can attributions to OH and peroxyde OOH groups be propose?
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Thomas has pointed out a major problem. Instrument vendors say that they will sell a diamond (or ZnSe) ATR and it is a universal sampling accessory.
Not true!
From those spectra it is obvious that you violated the critical angle constraint on ATR. I just finished recording a webcast for Spectroscopy, where this will be discussed. Single bounce (45° AOI) diamond ATR is not appropriate and even a Ge ATR element at a 45° AOI will still violate the critical angle constraint.
You may get usable spectra with germanium at a very shallow AOI. I would try a GATR or a VeeMax with a Ge element with a face angle of 60°. That should give you a large enough AOI to have it be greater than the critical angle for graphene.
You cannot interpret anything from these spectra until you get usable spectra. If you decide to do an external reflection experiment (which I don't think will work very well) you will need to correct them for the effects of the complex refractive index before you can interpret them.
As to your 7325 cm-1 feature you mention. That is still very much the infrared. It is the near infrared. And your spectra do not show it anyway.
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why not close
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this is simply a matter of quantum mechanics: Below the edge, the absorption related to this particular edge is zero - simply because the electron cannot be excited.
Above the edge, due to the transition matrix element (see Fermi's Golden rule), the probability to excite the electron into unoccupied states decreases, the larger the difference between the energy of the exciting photon and the binding energy of the photon is.
You may find a calculus e.g. in the book of Alford, Feldman & Mayer
Fundamentals of Nanoscale Film Analysis,
page 181 to 184.
Hope this helps, Dirk
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I have experimentally measured the absorption of a liquid solution using Cary 60 UV-VIS spectroscopy. I was also able to measure transmission (T%) and reflectance (R%) from UV-Vis spectroscopy. However, T% and R% curves seem to overlap in my measurement. I was also trying to go through the literature to know how to measure T% and R% from absorption. I have found the following relations.
1. Absorbance = -Log T
2. Absorbance = -Log R (No reference)
3. Absorbance = - 1 / [log10 (1/R)] (No reference)
4. R=1-√(T×e^A) (No reference).
I was wondering which one is the correct relation between absorption and reflectance for the UV Vis spectroscopy. It would be really helpful if anyone can give me a lead.
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May be simple problem: A = 1 - T - R
This equation is used in many papers.
example "The experimental results are shown in Fig. 1a,
b, respectively. From the R and T data, it is straightforward to obtain the absorption as A = 1 − R − T , which is of practical interest since it directly affects the optical efficiency."
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How can i calculate optical absorption in QE, where the zero phonon line would appear in the absorption curve
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In Quantum Espresso (QE), which is primarily a package for electronic structure calculations, directly calculating the zero-phonon line (ZPL) in the absorption spectrum may not be possible. QE focuses on electronic properties and does not include explicit calculations for phonons or the ZPL.
However, you can still obtain valuable information about the ZPL indirectly by performing calculations related to electron-phonon coupling or using post-processing tools. Here are some approaches and references that can help you gain insights into the ZPL:
1. Electron-phonon coupling: QE can calculate electron-phonon coupling matrix elements using the finite differences method. By computing the electron-phonon coupling, you can obtain information about the broadening and shifts in the absorption spectrum, which indirectly relates to the ZPL. You can refer to the QE documentation, specifically the dynmat.x code, for details on performing electron-phonon coupling calculations.
2. post-processing tools: After obtaining the electronic band structure and density of states (DOS) from QE calculations, you can use post-processing tools like Wannier90, BoltzTraP, or other analysis codes to calculate the optical absorption spectrum. These tools can incorporate electron-phonon interactions and provide insights into the ZPL position and intensity. Consult the respective documentation for these post-processing tools to understand their usage and capabilities.
3. External packages: Consider using other software packages that specialize in calculating optical properties, such as density functional perturbation theory (DFPT) or many-body perturbation theory (MBPT) approaches. These packages, like Yambo, ABINIT, or exciting, can include electron-phonon coupling and ZPL calculations within their framework.
When implementing these approaches, it is important to refer to the respective software documentation and research papers to understand the theoretical background, methodology, and practical usage of the tools.
References:
1. Quantum ESPRESSO (QE) documentation: https://www.quantum-espresso.org/resources/docs
2. Wannier90: A. A. Mostofi et al., "wannier90: A tool for obtaining maximally-localised Wannier functions," Comput. Phys. Commun. 178, 685-699 (2008).
3. BoltzTraP: G. K. H. Madsen and D. J. Singh, "BoltzTraP. A code for calculating band-structure dependent quantities," Comput. Phys. Commun. 175, 67-71 (2006).
4. Yambo: A. Marini et al., "Yambo: An ab initio tool for excited state calculations," Comput. Phys. Commun. 180, 1392-1403 (2009).
5. ABINIT: X. Gonze et al., "ABINIT: First-principles approach to material and nanosystem properties," Comput. Phys. Commun. 180, 2582-2615 (2009).
6. C. Friedrich et al., "exciting: A full-potential all-electron package implementing density-functional theory and many-body perturbation theory," J. Phys.: Condens. Matter 29, 383002 (2017).
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What are the absorption lines in the solar spectrum and what does the amount of solar energy collected by a solar collector depend on?
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The rate of energy collection is time dependent. Even on a clear day, the angle of the sun relative to the collector, θ, will vary with time of day and day of the year.The main parameters affecting the performance of solar collector are area, absorber absorptive and emissivity, emissivity of glass cover, temperature of absorber plate, collector tilt angle and number of glass covers. Selection of a solar collector type will depend on the temperature of the application being considered and the intended season of use. The most common solar collector types are: unglazed liquid flat plate collectors; glazed liquid flat-plate collectors; and evacuated tube solar collectors.A solar collector is a device that collects and/or concentrates solar radiation from the Sun. These devices are primarily used for active solar heating and allow for the heating of water for personal use. Absorption lines are dark lines, narrow regions of decreased intensity, that are the result of photons being absorbed as light passes from the source to the detector. In the Sun, Fraunhofer lines are a result of gas in the photosphere, the outer region of the sun. About 25,000 Fraunhofer lines are now known to exist in the solar spectrum, between the wavelengths of 2,950 and 10,000 angstroms.
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I want to use FDTD to simulate black phosphorus absorption A. Since black phosphorus is not in the material library, I add 3D new material by looking for the permittivity. The references are 'Jalaei, S., Karamdel, J. and Ghalami-Bavil-Olyaee, H. (2020), Mid-Infrared Photodetector Based on Selenium-Doped Black Phosphorus. Phys. Status Solidi A, 217: 2000483'. Then, simulation is carried out by referring to "Black antenna Mid-Infrared Photodetector with Circular Au/Pd Antennas". However, compared with BP photodetector without antenna, the negative performance of BP detector with antenna is worse. The absorption rate goes down. I'm puzzled. Can anyone help me out? Thanks!
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This is the relevant setting.
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How can I model the red circle part (Paper with 0.24mm thickness and Air with 6mm thickness) in figure1 (equivalent circuit model) in ADS?
Did I do the right job in figure 2(My model in ADS)?
Is there any component in ADS for dielectric layer in certain thickness?
Somebody please help me solve the questions.
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Now i use the ideal transmission line model to instead of paper and air. the impedance is calculated by the permittivity and permeability. The electrical length of the transmission line is calculated by the thickness and the impedance@Thomas Breuer
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Hello there , i did adsorption of methylene blue by chitosan and sodium alginate and bentonite bead, does occur absorption in the same time?
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Usually they talk about the absorption of gas in a liquid (water, alcohol). Methylene blue will be adsorbed on the surface of chitosan and sodium alginate and bentonite bead.
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Chloroform, able to dissolve PTCDI-C8 only in lower concentration. I want to make higher concentration solutions to get higher absorption.
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Dichloromethane (DCM), Toluene, Tetrahydrofuran (THF), Dimethylformamide (DMF)
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Dear sir/madam,
How to calculate the Specific Energy absorption. Please share some example calculations to calculate Specific Energy Absorption.
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@ Nekin, Specific energy absorption is defined as the energy absorbed per unit mass of material. Mathematically SEA = a/p, where p is the density of the composite material and IT is the mean crush stress. The attach file may help you.
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in order to quantify the concentration of Glycerol monostearate in aqueous solution by UV spectrophotometer, what is the maximum lambda of Glycerol monostearate?
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Dear friend Atefeh Shiri
The wavelength of maximum absorption for glycerol monostearate can vary depending on the solvent used and the concentration of the solution. However, a study published in the Journal of Lipid Research found that the maximum absorption wavelength for glycerol monostearate in methanol is around 230-235 nm. (Reference: https://www.jlr.org/content/16/6/674.abstract)
It is important to note that the specific wavelength of maximum absorption may vary depending on the instrument used and the experimental conditions, so it is recommended to conduct a calibration curve using different concentrations of glycerol monostearate and measuring the absorbance at different wavelengths in order to determine the most suitable wavelength for quantification.
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Hello!
I am curious , can anyone guide me how we can calculate the amount of hydrogen is stored in the metal hydride during the absorption process both in %wt. an in grams and how much energy is released during absorption
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Hello
To explain my answer I propose you what guided it;
It is difficult to know on which form the hydrogen is in the metal, that is to say it is in hydride form, atomic or molecular. The next difficulty is to measure its concentration. I approached these questions by studying the adsorption of incondensable gases on metals, atomically clean (Ta and Al (111)) at very low H2 partial pressure, of the order of 10^-3 Pascal and at room temperature. While the residence time of the molecules should be extremely short of the order of 10^- 10 seconds or less, it is much larger and depends on the polarity of the molecules and the presence of defects, impurities and dislocations. These defects create local variations of the crystal field and internal stresses while the adsorbed molecules create image charges that modify the electronic and vibrational structure at the surface of the solid. This is verified by electron spectrometry and is expressed by the dielectric function. Even at very low coverage, the adsorbed molecules become unstable due to the relaxation of internal stresses of entropic origin. This scheme is parallel to that of the effects of adsorbed charges on insulators and is expressed by an equation of state and expresses the surface barrier deformation by defects and the resulting physical/chemical adsorption and ion diffusion processes. On the basis of these elements, the hydrogen concentration of the order of ppm would not be measurable by weight but fatal to the cohesion. One can imagine several experiments to verify this scheme.
Have a nice day
Claude
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As you know, Beer-Lambert law is
I=I0exp(-a*d)
where a is absorption coefficient and d is sample thickness.
my question is if a ~104 cm-1 and d ~ 100 um, the I would be quite small compare to the I0. that makes hard to obtain
is there a way to measure absorption coefficient except ellipsometry in single crsytal?
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Just to add, there are two different levels of theory, namely the (Bouguer-)Beer-Lambert (BBL) approximation and the combination of Wave Optics and Dispersion Theory. The BBL approximation assumes that light has no wave properties (e.g., no interference effects, but also no reflection) and it also assumes that light does not polarize matter. Depending on the nature of your sample, such simplifications may be admissible. Additionally, most single crystals are anisotropic. This usually kills the concept of an absorption coefficient, because it only makes sense on the BBL level of theory (refractive index and absorption coefficient are wave properties!). Instead you have to determine the (complex) dielectric function tensor.
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During spectroscopic analysis of paclitaxal order from sigma, I am getting the maximum absorption of paclitaxal dissolved in methanol at 211 nm. However, according to the previously reported literature, it is between 227-230. I have cross-checked the results in three different instruments along with changing the cuvettes but the results are still the same. what could be the reason and also is it okay if I continue the further analysis at 211 only?
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yes. we have taken methanol as blank and the observed reading from methanol was subtracted from the tested compounds absorbance.
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My focus relies on obtaining the theoretical values for the PCT curve which I could plot and then compare with the instrument data to understand the concept better, I have elucidate what I have done and the direction which I am gravitating towards. I have assumed the absorption temperature at 25C and the saturated LaNi5 follows the stoichiometry of LaNi5H7
So I am trying to calculate the maximum amount of hydrogen which could be stored in the metal hydride (which is $LaNi_5$ here), Now I used the formula for the calculation as:
%wt. of Hydrogen in MH = \frac{molar mass of hydrogen}{molar mass of LaNi5},
I was able to get 1.605%wt. When converting into the %wt. of hydrogen stored I found the value of hydrogen in grams using the formula as:
grams of hydrogen as : \frac{%wt. of hydrogen}{100}*\frac{weight of metal hydride}{molar mass of hydrogen} * H/M here based on LaNi5H7, I took H/M as 7/6, the value for the hydrogen stored maximum was found to be 0.4094 grams , and 30 grams of LaNi5 was considered.
Now with an assumption of absorption temperature of 25C, I am trying to get the pressure at which this occurs based on the previous calculations , this could then help for me to do some PCT theoretical calculation, but the values which I obtained are very large pressures , usually not possible for this type of metal hydride, can please anyone guide me through any metal hydride calculations errors which I am pursuing and correct me or gravitate me towards the correct direction. (updates in the calculations could occur when the experimental results are obtained)
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Dear friend Ketan Karkare
Based on your calculations, you are trying to determine the pressure at which hydrogen is absorbed by LaNi5. The pressure-temperature-composition (PCT) curve is a useful tool for understanding the hydrogen absorption properties of metal hydrides. The PCT curve shows the relationship between the pressure, temperature, and composition of the metal hydride. The theoretical calculations for the PCT curve can be obtained using thermodynamic models such as CALPHAD (Hydrogen sorption...).
The Gibbs energy for LaNi5-xAlxHy (0 ≤ x ≤ 1, 0 ≤ y ≤ 7) phase was obtained using a full CALPHAD assessment. The results showed good agreement between experimental and calculated results (Hydrogen sorption...).
It is important to note that the PCT curve is influenced by various factors such as temperature, pressure, and composition of the metal hydride. The idealized PCT curve is shown in Fig 1 (NIST-MSEL hydrogen...).
I hope this helps! Let me know if you have any more questions.
Source:
(2) NIST-MSEL Hydrogen Storage Program: Research - Introduction. https://www.ctcms.nist.gov/hydrogen_storage/tutorials_PCT.html.
(3) Surface Properties of LaNi5 and TiFe—Future Opportunities of .... https://www.frontiersin.org/articles/10.3389/fenrg.2021.719375/full.
(4) LaNi5 related AB5 compounds: Structure, properties and applications. https://www.sciencedirect.com/science/article/pii/S0925838820345266.
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Absorption constant of metal hydride
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I accidentally found your post. The robot does not send a message unless the name is clicked with "Mention". The constant Ca is determined experimentally in each particular experiment.
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How do I convert ytterbium ion absorption of 280 dB/m at 920nm into db/m at 977nm?
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Concerning your problem at hand, the only possibility is imho that you measure the transmittance of your fiber at the wavelength you are interested in and determine the absorption coefficient from the measured transmittance.
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Dear QE users,
I want to plot the optical properties of a crystal. I'm working with ultrasoft pps, so the only option I found to obtain it was to calculate these properties using the Turbo-Lanczos package in QE. I got two files, the plot_S.dat, and plot_chi.dat.
If I understood it right, the plot_S.dat can be used to plot the absorption spectrum. In the plot_chi.dat, the program created a matrix with Real and Imaginary parts of the dielectric constant, as follows:
\hbar \omega(eV) Re(chi) (e^2*a_0^2/eV) Im(chi) (e^2*a_0^2/eV)
chi_1_1= 0.0000E+00 0.251513E+02 -.00000E+00
chi_2_1= 0.0000E+00 0.289682E-01 -.00000E+00
chi_3_1= 0.0000E+00 -.627424E+01 0.0000E+00
chi_1_2= 0.0000E+00 0.287160E-01 -.00000E+00
chi_2_2= 0.0000E+00 0.316761E+02 -.00000E+00
chi_3_2= 0.0000E+00 -.136008E-01 0.00000E+00
chi_1_3= 0.0000E+00 -.627868E+01 0.00000E+00
chi_2_3= 0.0000E+00 -.1321167E-01 0.00000E+00
chi_3_3= 0.0000E+00 0.250771+02 -.00000E+00
chi_1_1= 0.10000E-01 0.251513E+02 0.908418E-03
......
How can I use this data to plot the real and imaginary parts of the dielectric constant, and the absorption in the directions [001], [010], [100]?
Thanks for your help!
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To plot the dielectric function in different directions, you can extract the relevant elements from the matrix. For example, if you want to plot the dielectric function in the [001] direction, you would need to extract the elements chi_3_3, chi_3_1, and chi_3_2, which correspond to the xx, xy, and xz components of the dielectric function. Similarly, for the [010] direction, you would need to extract the elements chi_2_2, chi_2_1, and chi_2_3, which correspond to the yy, yx, and yz components of the dielectric function, and for the [100] direction, you would need to extract the elements chi_1_1, chi_1_2, and chi_1_3, which correspond to the zz, zx, and zy components of the dielectric function.
To rotate your crystal, you can use the 'cell_parameters' keyword in the input file for the Lanczos/Xpectrum calculations. You can specify the orientation of your crystal by changing the lattice vectors. For example, to rotate your crystal so that the [001] direction is aligned with the z-axis, you can set the lattice vectors as follows:
cell_parameters
1.0
a1 a2 0.0
a3 b1 b2
0.0 0.0 c
/
where a1, a2, a3, b1, b2, and c are the lattice parameters of your crystal. By adjusting these parameters, you can align your crystal with any desired direction. Once you have rotated your crystal, you can perform the Lanczos/Xpectrum calculations as before to obtain the dielectric function in the desired direction.
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I am working on clay modification. The problem in this experiment is that when the supernatant solution in the centrifuge tubes is discarded after centrifugation (9000 rpm in 20 minutes), large amounts of fine clay particles are also removed with it. These particles are very important for the absorption and swelling ability of the clay, and when they are removed, the efficiency of the clay decreases. Is there a way to prevent the release of these particles and settle them?
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Dear kaushik
I can not to add any chemical in my solution because mybe effect on other element and chamecal existing in centrifuge falcon.
thanks for your reply
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Hello, One of the problems of gC3N4 in the photocatalytic activity of dyes is dye absorption. Is there a solution to prevent the absorption of methylene blue by gC3N4?
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Amirreza Ojagh, you will need to take care of the surface properties of the synthesised catalyst. In your question you have not elaborated the synthesis method and how you confirmed there was adsorption of the catalyst on the substrate.
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How I calculate refractive index from absorption coefficient cm-1
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You can use the Strickler-Berg formula for this. You can look up equations (2.26) in my book:
Photoprocesses in biomolecules, carbon nanoparticles and polymer solar cells (Full text)
Full-text available on RG
Book
• April 2016
• Vladimir S. Pavlovich
• I wish you success.
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In literature varied uv absorption range of AG Nps formed are given and varied colour also. From yellow to green. But i am getting dark brown (BLACKISH) colour does this confirms the formation of Ag Nps? In my analysis i am getting UV absorption peak at 490nm. is this correct?
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Susanna Gevorgyan Thankyou so much dear for your help and so supportive information
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Is absorption capacity can be increased by increasing the porosity of hydrogels (for example, k-carrageenan)? If yes, then what are the physical processes and what are the components that can be added to increase the absorption capacity?
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Hydrogels are polymer networks that can absorb and retain large amounts of water. The absorption capacity of hydrogels depends on several factors, including the type and number of hydrophilic groups present, the degree and type of cross-linking. In addition, environmental conditions such as temperature, pH, temperature and ionic strength can also affect the absorption capacity of hydrogels. To increase the absorbency of hydrogels, several methods can be employed, such as:
(i) Use blending or copolymerization: Blending carrageenan with other hydrophilic polymers or copolymerizing it with other monomers (like acrylic acid) can create hydrogels with enhanced water absorption capacity. (ii) Optimize processing conditions such as, amount of cross-linking agents, temperature, pH, or ionic strength of the solution, can affect porosity of the hydrogel, and thus the water absorption capacity. (iii) Incorporating nano/micro fillers into the hydrogel can create additional swelling sites and improve water retention capacity.
It is important to note that the optimal approach to increasing the absorbency of hydrogels depends on the specific application and desired properties.
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I need experimentally determine optical absorption coefficient and refractive index changes in quantum dots
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Thank you for your answer. Can I use these techniques to determine second and third harmonic generation in quantum dot?
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Which metal film will be better for use in optical thin film setup to enhance light absorption in MoS2?
(Cu, Au, Ag, Al)?
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This is not in my disciplinary area.
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My question is that either we can draw the absorption spectrum directly by FDTD or we use any other software to represent it because reflection and transmission can be draw directly by FDTD but how absorption spectrum. Please guide me in this regard if it is directly from FDTD then guide me how we draw spectrum of absorption from FDTD or share any tutorial for this.
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FDTD cannot directly calculate absorptance (or absorbance), but if you have the reflectance and the transmittance spectrum, then you can calculate absorptance A by A=1-R-T for every wavelength point. Similarly you get absorbance A by A=-log10(T+R).
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I'm working on absorption enhancement in Multiayers with nanomaterials. I want to know which monolayer structure is better for more light absorption? MoS2 or WS2?
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The monolayer structure of MoS2 is better for light absorption. MoS2 has a larger band gap and higher light absorption than WS2, which means that more photons will be absorbed and converted into electron-hole pairs when passing through the monolayer. Additionally, MoS2 has a higher extinction coefficient than WS2, meaning it can absorb more light over a greater range of wavelengths.
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I am simulating a solar powered absorption chiller. But I want to manipulate ots working time. For example, the system will run from 6 am to 10 am, then a break of 4 hours and then again run for four hours and then stop. How do I achieve this ?
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Dear Auritro Samanta,
Maybe my answer is too late for you. However, it can be helpful to others.
One option to manipulate TRNSYS simulations is by the 'dck' file that can be generated from the TRNSYS model (the tpf file).
The dck file is a plain text command line file, which TRNSYS reads and executes the codes.
TRNSYS can be started from the prompt to execute a dck file by the following command: <[trnsys_path] [dck_file_path] /h>.
The </h> will hide the trnsys window, and it will be executed in the background.
Thus, you can write the tpf model with some tags, generate the dck file, search in the dck for the tags that you used, and then replace the tags with the values you want to use.
I hope this can be helpful to someone.
Kind regards,
André.
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Can anybody suggest me to find out the reason behind the continuous absorption of UV light in biomass carbon? How to interpret the following absorption spectra?
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Could you explain how you mage your measurement?
I suspect that this is reflectance, R, which means that to show Absorbance (which has no units), you should calculate
-log10R
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Uv- Visible study.
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These are some factors to consider when choosing a method:
Sample type: The Tauc plot method is suitable for measuring the bandgap energy of transparent materials, while the Kubelka-Munk method is suitable for measuring the bandgap energy of opaque materials.
Absorption coefficient: The Tauc plot method requires a precise measurement of the absorption coefficient, which may be difficult to achieve for weakly absorbing materials.
Scattering effects: The Kubelka-Munk method is less sensitive to scattering effects, which can be a major source of error in the Tauc plot method. However, the Kubelka-Munk method assumes that the material is homogeneous and non-absorbing, which may not be true for some materials.
Measurement range: The Tauc plot method is suitable for measuring the bandgap energy of materials with a narrow absorption edge, while the Kubelka-Munk method can be used to measure the bandgap energy of materials with a broader absorption edge.
Check this for more detailed information: https://doi.org/10.1021/acs.jpclett.8b02892
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And this absorption rate of TMB by uv vis depends on what factors
And whether the oxidizing agent of TMB is also effective on the amount of absorption at 650 wavelength
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The absorbance of a solution at any given wavelength is directly proportional to concentration of the absorbing substance, as long as the concentration is not too high for other effects to come into play. The constant of proportionality is called the extinction coefficient. The absorbance is also directly proportional to the distance light travels through the solution. Overall, the relationship is called Beer's Law or the Beer-Lambert Law.
If there is more than one substance in the solution absorbing light at the given wavelength, the overall absorbance will be the sum of the absorbances of the individual components, as long as there is no interaction between the substances. If there is a chemical reaction between them, the situation is more dynamic, and the absorbance will change over time as the reaction occurs.
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Metamaterials simulation.
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How is Comsol simulation different from fdtd simulation?
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Is there any relationship between stl and absorption coefficient?
Suppose i am getting a peak at 400Hz (90% absorption) then at the same frequency what will be the sound transmission loss(it will be minimum or maximum or we can not say).
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The absorption coefficient of a panel or a membrane will according to Ver and Beranek have a transmission loss component 10^(-R/10) + a panel or mambrane dependant term. It is briefly described in this article draft with the reference:
This may be relevant eg for outdoor «stage bubbles», »bubble tennis courts», tents, or simply for light walls with somewhat low sound insulation. At low frequencies the transmission term of the »absorption» may be 0,1 or even higher.
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Often, XRD analysis of powdered carbon based materials, e.g. carbon blacks, are not reproducible (preparing the same sample different times for analysis), with a high variation of the S/N ratios, and different levels of background to be subtracted.
The latter problems make difficult to compare between different samples and draw more in depth conclusions about the effect of treatments, and so on.
I am currently using Si single crystal based sample holders with 0.2 mm depth, as recommended for carbon, due to its low X-Rays absorption coefficient making the reflected radiation coming from the inside of the sample.
Is there a standard way of preparing carbon based samples? How is it possible to improve the analysis reproducibility?
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Hi Gianfranco,
There are several sample preparation procedures that can be used to improve the reproducibility of XRD analysis of carbon-based materials, as well as the signal-to-noise (S/N) ratio:
1. Grinding and sieving: One common approach is to grind the sample to a fine powder and sieve it to ensure a consistent particle size. This can help to improve the reproducibility of the analysis and also increase the S/N ratio by providing a more homogeneous sample.
2. Annealing: In some cases, annealing the sample at a high temperature can help to improve the crystallinity of the material, which can lead to better XRD patterns with higher S/N ratios. However, it's important to note that annealing can also introduce other changes to the sample, such as changes in the surface chemistry or the formation of new phases, so this approach should be used with caution.
3. Sample orientation: By orienting the sample in a particular way, it may be possible to enhance the intensity of certain diffraction peaks and improve the S/N ratio. For example, if the sample has a preferred orientation (i.e. a tendency to align in a certain direction), then orienting the sample in a particular way can help to enhance the signal from certain crystal planes.
4. Use of a reference material: To improve the reproducibility of XRD analysis, it's often useful to use a reference material that has well-known crystallographic properties. By comparing the XRD pattern of the reference material to that of the sample, it's possible to identify the phases present and determine their crystallographic properties more accurately. This can also help to improve the S/N ratio by providing a known signal that can be used to normalize the data.
Ultimately, the choice of sample preparation procedure will depend on the specific characteristics of the carbon-based material being analyzed, as well as the specific goals of the analysis. It's always a good idea to consult the literature and seek advice from experts in the field to determine the most appropriate approach.
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And is the type of copper oxide nanoparticle synthesis method effective on the wavelength and amount of uv_vis absorption?
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The UV-vis absorption spectrum of copper oxide nanoparticles synthesized chemically can span visible light to near-infrared regions, with the exact range depending on the specific type of copper oxide and the synthesis method used. Generally, the absorption of copper oxide nanoparticles synthesized chemically peaks in the visible to near-infrared regions at around 400 to 800 nm.
The type of copper oxide and the synthesis method used can significantly affect the wavelength and amount of UV-vis absorption. For example, the synthesis method can affect the nanoparticles' size, shape, and crystal structure, all of which can influence the absorption spectrum. Additionally, the composition of the surrounding environment, such as the presence of solvent or surfactants, can also impact the absorption spectrum.
In summary, the UV-vis absorption of copper oxide nanoparticles synthesized chemically can vary depending on the specific type of copper oxide, the synthesis method used, and the surrounding environment.
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If it does, how does the situation look for crystalline and amorphous materials?
Suggestions of papers/books to educate me on this topic are appreciated.
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Yes, the absorption coefficient of laser radiation by a material can depend on the beam polarization. This is because the absorption of light by a material depends on the orientation of the electric field with respect to the crystal lattice or molecular structure of the material. For example, in anisotropic materials, the absorption coefficient can be different for light polarized in different directions. In other materials, like many liquids and glasses, the absorption is isotropic and independent of polarization.
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recently I am building home-made UV-Vis absorption spectrum set-up in our lab, but the big problem is happened.
What I am going to do is obtain absorption spectrum of perovskite, but, as PL of it is so intense, PL appears in the absorption spectrum.
we have to remove PL from absorption data, but just substract PL is not helping.
Do you know how to remove PL from absorption data?
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Jeong Bin Cho It would be very interesting to look at the distortion of the spectra. My last idea is to maximize the optical path, since the luminescence is non-directional, unlike the light absorption signal.
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Hello,
Do you know where to find the infrared absorption cross-sections or line strengths of trioxane in the gas phase? Found several FTIR spectra of trioxane but these only provide relative absorption cross-sections.
Thanks,
Stefan
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Joële Viallon Hello Joële, such a spectrum would definitely be useful for us.
Thanks!
Stefan