Questions related to Spectra
Actually I tried it in QE but the only problem arising where the output file shows no symmetry found. How to turn on that symmetry? (The ibrav tag is given properly)
My research work involves concentration measurements using a laser-induced fluorescence technique with silicone oils as working fluids. Silicone oils being highly hydrophobic in nature complicates their mixing behavior with typical commercially available inexpensive fluorescent dyes.
I understand there are solvent-based oil-soluble dyes used in petrochemical industries though as far as I know, they fluoresce in the ultra-violet wavelength range.
I also understand that the emission/absorption spectra of fluorescent dyes are also solvent-specific and studies pertaining to that are limited. So I was wondering if anyone is aware of dyes that would mix homogenously with silicone oils and fluoresce in a 527 nm wavelength Nd: YLF laser light source.
I run the CD spectra of the modified and non-modified protein and the 2ndary are the same. However, there is a change in amide I in the FTIR results. Thus, the functionalization might be expected to change the secondary structure. Kindly any suggestions with references.
I am fairly new to FTIR and I am analysing some inks using ATR. The obtained results were processed using the same background, and plotted against a common scale. When interpreting the results, (a) I notice that the spectra looks very different in Transmittance vs. Absorbance. Is this real? Or could be an artifact of the way the sample interacts with the crystal (e.g. should I repeat the measurement)?
(b) Also, it seems that there is a real vertical offset between sample blue and sample purple. If that is the case, does this suggest that one is overall more absorbent / transmissive than the other?
I study on some kind of infrared barrier and I don't know how to calculate normalized reflectance spectra weighted by human body radiation?
For example you can see results of this article but authors did not mention the calculation method:
Based on my understanding, the absorption of infrared for example, band at ~1000 cm-1 caused by the absorption infrared by the Si-O bond in FTIR spectra. So, the XRD results will show a strong peak at a certain 2-theta to show that the SiO2 is there. Is it correct?
Hi everyone, i have work using paracetamol sample with electrochemical wastewater treatment under special conditions, then analyze with COD (Chemical Oxygen Demand) removal, UV and FTIR.
Analyze by the COD removal, the COD removal is high which were up to 70%. The UV spectra shows that the UV peak were reducing between control and treated. But, the FTIR spectra shows that the FTIR of control (untreated Paracetamol) in blue curve and that of treated in purple curve were same like there's no difference. Whereas, based on the COD removal and UV spectra there is a difference. Can anybody tell the reason why the FTIR curve like that? Is it okay if the curve of FTIR like that? "If the the absorbance of the uv peak were reduces, then the transmittance of the FTIR also reduces" is that statement true? The FTIR curve were confusing, so I need your help.
Thanks in advance...
I am working on microplastic contamination in the water samples, and I have prepared the samples as per NOAA. Still, when analyzed using FTIR (Bruker - ATR mode), the transmittance spectrum is more than 100% (nearly 102 or 104). Please explain how to get rid of these and interpret the results?
I am attaching the raw spectra for reference
Thank you in advance
I have FTIR spectra of plastics and I need to identify their chemical composition. there's any software or database for this issue?
I found Poseidon, but I don't know the process or parameters about it...
Thank's in advance for your answers
The blue curve in the attached figure is representative of a thermally treated (1000C) pellet of carbon-13 where the orange curve is for a pellet that was cured at 150C.
The literature for locations and interpretations of Raman spectra bands of amorphous carbon seems...a bit unorganized.
Following Ferrari's amorphization trajectory, I would interpret the increase in Id/Ig between the two as an increase in structural order (going from aC to nC graphite), also following the slight increase in the Gpeak position. Similarly, the D3 band seems to be associated with an amorphous structure. The reduction in D3 intensity would also indicate a decrease in the disorder and higher concentrations of sp2 sites.
I am wondering if those more experienced come to the same conclusion, what the more pronounced separation of D2 and G bands would indicate in the heat-treated samples, and what other information anyone would pick up from these two spectra.
I made an experiment with polymers and how UV irradiation changes the surface structure. Therefore, ATR spectra of pristine, 24 days and 48 day aged polymer pellets were taken. Now I want to quantify if a significant change occurred.
I am currently working with R, so I would be very thankful for R compatible ways. Thank you in advance.
I have commissioned four Raman analysis last week.
But when I looked at data, one of it looks like somewhat enlarged.
It's intensity was about 10 times larger then others.
(one data shows intensity range from 3000 to 13000 while others show 200~1500)
I want to compare two of them, but it's hard to see peak of smaller spectra due to propotion difference. I could shift data parrel to y-axis if it was just baseline difference, But can I shrink/enlarge data to y-axis direction?
I have attached part of my data.
thank you for your time.
I am mentoring a trainee who is writing a dissertation on phototherapy for neonatal jaundice. She has been using a spectroradiometer and has noticed that the spectra from LED-based units are all slightly asymmetric. I have also noticed this in publlished papers. In the attached drawing I have exagerated the effect, where the emission of wavelengths longer than the peak emission, but many spectra that I have seen show this effect. Anybody know why this may be?
Thanks in advance
Hello, this is my first post on this site. I'm an undergraduate student doing some Raman spectroscopy of CVD-grown graphene strained on silicon dioxide nanospheres. I notice that D and G' peaks show up in some measurements. The transfer process of the graphene to the silicon dioxide nanosphere-coated silicon chips I would think is far from perfect, as in certainly interferes with the structure of the graphene as there are rips and tears across the sample, as well as impurities and other things. You do however have "pristine" regions that only show G and 2D peaks.
On a loosely related tangent, I'm interested in how the molecular symmetry of graphene plays a role in its Raman spectra, and how that can be expressed mathematically. I wonder if perhaps the mathematical description of graphene in terms of group theory can possibly help explain the redshifts that occur in strained graphene versus unstrained graphene. If anyone has some advice or things to read about that, please let me know!
I have two questions, actually:
1 - Is it possible to "drag" one spectrum to reposition it against another spectrum for a better match/comparison? I know I can go to Process > X Offset and adjust but can I do it using thus the mouse?
2 - When I'm pasting the spectra directly into Spectragryph's canvas is there a way to keep the unity used for x and y axis fixed? most of the time when I paste the second spectrum it changes the units to cm-1 and mess with the whole view.
I am using Spectragryph V1.2.15 to visualize FTIR Spectra. But it is showing values in "nm" on x-axis. When i chose the "wavenumber(1/cm)" instead of "nm", it changes the range to 16000-25000. Please suggest where can be the problem?
Currently, I want to compare between the output power of a rooftop PV system which can be obtained direct measurements of (Isc and Voc) and the estimation power output of C-Si based on the incident solar spectra and spectral response.
Similarly In XAS (X-ray absorption spectroscopy) spectra for 3d elements, why BE of the L3 edge has lower in energy than the L2 edge?
I want a program that i can use to get the raman spectra of crystals not just molecules. Do you have any idea of how i can do that and if there is some way to do it using python.
I have come across studies which have mentioned Raman and FTIR to be complementary. So, why are some bands present in FTIR but are absent in Raman or vice-versa.
I have acquired my Raman result of microplastic in SPA files, but i have trouble in identifying them. I also found reference spectra from the Spectragryph website (https://www.effemm2.de/spectragryph/down_databases.html) but I can't find how to match the reference with my Raman result. Is there a way to do so in Spectragryph?
I have three MS spectra of an unknown protein. The protein has been separated and directly analyzed with a MS without trypsinization (top down approach). How can I know the identity of the protein? I suppose I can search for a matched spectrum in a library. However, I have no experience with top down proteomics and I don't know which software to use for the protein identification. Any help please?
When I run a fluorescence spectra measurement on Jasco FP-8300 Spectrofluorometer, the intensity does not exceed 10000 even after changing the scale. As shown in the picture, once the intensity reaches 10000, I get this plateau. I would like to ask whether it's a parameters issue or a machine issue; and if there is a way to fix it?
Thank you in advance.
It is known that bands at 2920 and 2850 cm-1 in FTIR spectra are assigned to the asymmetric and symmetric stretching vibrations of (CH2) groups.
One peak at 1920 cm-1 was observed in the FTIR spectra of the control treatment in my experiment, but when the plant was subjected to varied salinity levels, a new band at 2850 cm-1 appeared.
Anyone who could assist me would be greatly appreciated.
I have the Raman spectra for WO3 samples. I have peaks at 270, 324, 714 and 805 cm-1 for the stretching and bending modes of O-W-O. A small peak for the W=O can be observed at 943 cm-1. For which peaks should I calculate the ratio? Also how do I interpretate the results? (eg: if the ratio is smaller than 1 or close to 0.5, respectively 0 - what would that mean?). Thank you in advance!
More specifically, I want the comparison in wavenumber-based power spectra, opposed to frequency-based. That would include converting multiple signals into a cross spectrum, finding the phase, and then the final conversion to wavenumber.
Extra points if it is in the field of plasma physics and magnetic signals.
Thanks in advance!
Why the values of the intensity ratio of doublet spectra of the laser-produced plasma spectrum differ from the theoretical value of the intensity ratio given in NIST data.
I am currently working on characterizing Pd(111) using XPS but I keep getting a low electron count( Intensity)
I am observing two distinct peaks in the XPS high-resolution spectra of O 1s, (the sample is a nanoparticle colloid and Oxygen is only coming from the solvent) the nanoparticle are multimetallic, is it possible to identify which element is forming the oxide by analyzing the O 1s spectra alone.
The researcher shows the CD spectra data wherein x-axis it is wavelength but in Y-axis it is written CD (mdeg), why not ant fixed technical term which can relate both ellipticity and absorbance. the unit of cd signal is deg•cm2•dmol-1 is there any other term we can use in this replacement that Is meaningful and accepted.
I am investigating interactions of poorly soluble pharmaceutical (nabumetone) with cyclodextrins in solution and solid-state. Complexes of nabumetone and beta cyclodextrins were prepared in different molar ratios by grinding in high-energy vibrational mills and corresponding physical mixtures were prepared using a mortar and the pestle as well (n:n = 5;1, 3:1, 2:1, 1:1, 1:2, 1:3 and 1:5). In the ATR spectra of ground samples with higher content of the pharmaceutical, I noticed an increase in the intensity of characteristic bands of the pharmaceutical (in comparison to corresponding spectra of physical mixture) but I didn't observe the same phenomena in the corresponding transmission spectra. Usually when these kinds of samples are investigated by infrared spectroscopy decrease in the intensity of the characteristic bands of the guest molecule is explained by the inclusion of the molecule in the hydrophobic cavity of cyclodextrin. What is the possible cause of these increments in nabumetone band intensities in ATR spectra? Why aren't these increments visible in transmission spectra as well?
In laser-induced plasma spectra, an element usually has multiple lines corresponding to it. In theory, how to determine which lines are most likely to excite? In addition, there are two elements in a sample with the same content, the same energy level, the same transition probability. Why are atomic lines detectable for one element and not for another?
- The transmittance spectra is from a coloured TiO2, but after converting to absorbance, the absorbance spectra look so strange. I used the equation ABS=2 - log(T%). I do not know what is wrong. Because of the transmittance spectra, the line was lightly increased between 350 nm to 400 nm, but for the absorbance spectra, it has a straight increase. I attached the files I did. Hopefully, there is an expert who can help me to work on that.
I want to study blood samples by KBR to visualize spectra occurring between 900 and 1100cm-1. Specifically to see the behavior of glucose and insulin. In fact I would like to know if I can study glucose and insulin solutions by KBR, ¿how do these liquids affect the potassium bromide tablet and the spectra?
¿Could you help me with any reference in the literature that talks about the types of samples that are studied in KBR and why we can't study liquids by this method?
I am trying to recover RNA from nerual N27 cells that I encapsulated within Alginate hydrogels. I am using the PureLink RNA Mini Kit, using the manufacturer's protocol (Starting on pg. 14: https://www.thermofisher.com/document-connect/document-connect.html?url=https%3A%2F%2Fassets.thermofisher.com%2FTFS-Assets%2FLSG%2Fmanuals%2Fpurelink_rna_mini_kit_man.pdf&title=UHVyZUxpbmsgUk5BIE1pbmkgS2l0 )
I believe I have successfully recovered RNA from plain cells in suspension. I attached the NanoDrop Spectra (Cells Only Control RNA.PNG). The 260/280 was 2.1, and the 160/130 was 1.86. The concentration was 229.8 ng/ul.
However, I have been struggling to recover pure RNA from cells in alginate hydrogels. Like with the plain cells, I rinsed them 3x in cold PBS, which broke up the alginate, and tried adding an extra Wash Buffer 2 rinse. The results (Cells in Alginate RNA.PNG) had a nucleic acid conc of 51 ng/ul, a 260/280 of 2.1, and a 160/130 of 0.09, indicating a contamination of some salts/phenols.
Is there any way to purify my sample so that I can carry out qPCR?
I appreciate your guidance!
could I ask, please, what is the best software or platform for identifying RAMAN Spectra of Microplastics ? Best if it's a free version.
I have the LCMS chromatograms and spectras of plant extracts, need help/ advice for LCMS library search to identify compounds present in the extracts.
Collected the FTIR spectra of an unknown polymer sample and tried to match with my database.
But it is not matching with any entry of my database. Indeed quite different from the existing entries. So please help me out in identifying its chemistry and how can I do it in future?
I have used OSRAM tools, as well as LabCognition Panorama and chrislinbloom. com spreadsheets to compute the perceived color from Uv-vis spectra. When I choose a UV-Vis absorbance graph of a completely colorless sample (i.e. absorbance at all wavelengths equal to zero) the color returned by the program is black, instead of white. For "real" spectra" I sometimes get sensible results, and other times (e.g. when selecting a spectrum with a single absorption peak around 400 nm) I get strange results with negative values for one of the three color coordinates. Does anyone have some suggestions regarding (e.g.) mathematical limitations of the conversions formulas used, or whether I should convert my absorbance graphs to transmitances, photon number, or whatever?
I am confused at to the broad peaks, for example between 3400 and 2800 cm^-1. I am having difficulty in this respect
I am doing a 2D simulation of gold electrodes on a glass substrate immersed in liquid - typically biological solutions, such as PBS with ionic strength of around 100mM. In particular, I am simulating the complex electrical impedance as a function of frequency (basically electrical impedance spectroscopy - EIS). Is there a way to stimulate the presence of the EDL in order to include its screening effects in the EIS spectra? I am currently using the AC/DC module, do I need to use a different one? Which parameters should I know to simulate the formation of the EDL?
I recently tried to do a D-parameter calculation for reduced graphene oxide, and the value came out to be 21. This corresponds to >70% of sp2 contribution as per the available literature of XAENS. I doubt whether the same calculation can be applied to XPS? Any good literature suggestion is highly appreciable.
I have two samples of the same compound and I suspect they are contaminated with acidic impurities. I record 1H NMR spectra in CD2Cl2 and in pure NMR solvent I observe a nice narrow singlet for H2O at 1.53 ppm. When I record the spectrum of one of the samples of my compound (which I assume has less acidic impurities), the water peak disappears and a broad singlet at 1.9 ppm appears. When I record the other sample (presumably more acidic), the broad singlet appears at 4.0 ppm. Then I spike one of the samples with AcOH and along with the CH3- singlet, I now see the broad singlet at 7.3 ppm.
My hypothesis is the following: When acids are present in the sample the H2O signal in the NMR spectrum shifts downfield (gets deshielded). Can anyone confirm/reject this?
Thanks in advance!
Dear all, I am using metabolic fingerprinting for my clinical studies. I am in doubt that I can use the Raman spectra for quantification? Can I use it semi-quantify? Can you provide me with references? I have biological fluid such as serum, seminal plasma or milk?
I'm currently trying to find the differential cross section for the products following proton irradiation of Si. something like the attached plot [Barak et al, Trans. Nucl Sci 2001] but at different proton energies. I believe the reaction is 14 Si(p,X), and I believe the data would be MT=5 in the ENDF data base. But I seem to be stuck in converting ENDF into something that would be easily readable.
I'm having difficulties comprehending how MS and MS/MS spectra are obtained in regard to eachother.
In easy words:
A package of ions ("package 1") is eluted from the LC and MS spectra are obtained from these ions. From these spectra, the most abundant ions are chosen for further dissociation for MS/MS spectra. My question is: the ions used for dissocation is coming from a different package ("package 2") of ions eluting from the LC, since the "package 1" has already been used for MS. How do we know whether the ions chosen for dissocation, based on the MS results of "package 1" can also be found in "package 2"?
I have synthesised quantum dot using green synthesis. Uv vis spectra show peak at 270 nm(protein peak) and 400nm(quantum dot peak). Excitation wavelength for PL measurement is 390nm but i get broad spectra. What is the reason behind this.
I am having a difficult time getting Raman spectra for monolayer MoS2. I have used various substrates (Au, Si/SiO2, Au TEM grid with 5-6nm carbon support) but i have been unable to achieve a proper spectrum unless measuring a sample that is several layers thick or 10s of nms. I typically use a 532nm laser, <1 mW power, and 100x objectification lens. I have also varied measurement parameters like exposure time (10-300s) and number of accumulations (1-25) without luck. Am I missing something? I would have thought it was more straightforward. Thank you in advance for your suggestions
As you may know, the site-specific response spectra are usually limited to 5 seconds, while in many cases, such as the design of long-period structures, we need to have the spectra up to 10 or 20 seconds. The problem is even the GMPEs are usually limited to 10 seconds! I was wondering, is there any method to extrapolate the spectra from 5 seconds to 10 or even 20?
As per my knowledge, the EIS technique is used for calculating various impedances like Rs (Solution or equivalent series resistance), Rct (Charge transfer resistance), etc. However, is it possible to calculate separator resistance using the EIS technique, and what component of the EIS spectra can help in recognizing the same?
We have 600-600-600 spectra for 3 treatments.
We are looking for a statistical method (or program) to distinguish significant changes in peaks.
Thanks in advance!
I have synthesized cerium oxide nanoparticles via hydrolysis method using NaOH. I obtained yellow precipitates at the end of reaction indicating synthesis of cerium oxide nanoparticles. But in UV vis spectral scan showing two small humps around 225 and at 350 nm. The FTIR spectra showed absorbance peak at 664 cm-1. In literature, FTIR peaks of cerium oxide nanoparticles are reported at 476 cm-1 (Ce-O stretching), 556 cm-1 (O-Ce-O) and 668 cm-1 (Ce-O) stretching mode. I also have peaks at 1055 and 1318 cm-1 for nitrate.
Does that indicate reduction wasn't complete?
Or Calcination is necessary for Ce oxide nanoparticles synthesis?
I have attached the UV vis spectrum.
Thanks in advance for your assistance and guidance.
Discussing the FTIR spectra and XRD patterns of barium titanate samples in the literature is diverse and somewhat contradicting. Some researchers are looking for a desirable and justifying reference. One of the main aims of the following article is to address the demand:
The full-text of the article has been attached.
I used two samples, one of pure SiO2 and one of pure Al2O3. For each sample I obtained the corresponding ATR (attenuated total reflection) and DRIFT (diffuse reflection) spectra. The spectra look very different from each other, they seem to be from totally different samples. What can this be due to? For both measurements I used an FTIR spectrum of KBr as Background under the same conditions of each measurement.
Spectrometer: Nicolet™ iS50 FTIR
Spectral range: 4000 – 400 cm-1
Resolution: 4 cm-1
Background and sample scan: 32
Zero filling factor: 2
Apodization function: N-B Stark
Phase correction mode: Mertz
Detector: DTGS ATR
Beam splitter: KBr
Background and sample signal gain: Auto
Mirror velocity: 0,4747 cm/s (ATR), 0,0317 cm/s (DRIFT)
Aperture setting: 100 (ATR), 200 (DRIFT)
Accesory ATR: Smart iTR™ Attenuated Total Reflectance (ATR) Sampling Accessory
Accesory DRIFT: The PrayingMantis™ diffuse reflection accessory (Harrick Scientific Products)
Is it any possibility to compare relative positions of Fermi level of different materials with given XPS valence-band spectra? If spectra are well-calibrated, Fermi level shoud be at 0 eV, thus, Fermi level of all measured materials should be equal, what - obviously - is generally not true. I am surely missthinking, but I'm not able to find any mistakes. Could anyone help me to solve this problem?
I am doing a microthermometric investigation of my fluid inclusions, I'll be using different equations of state with some of the available programs (Uni Leoben fluid inclusion programs, SoWat, etc.). I want to make a plot of the isochores calculated with the different EoS's for different FIA types in a way that they cover a certain area in a p,T- diagram. Any suggestions on a nice program to do this?
I'm suspecting that I'm having a ternary water salt system for the fluid inclusions in my sample. The freezing temperature is mostly around - 55 centigrade, the initial melting occurs at about - 45 to - 35 centigrade. It's tricky to determine the exact one even with cycling. The final melting temperature is mostly around - 16 centigrade. How would I exactly determine these datasets in terms of whether it's a binary or ternary system? The crystals which appear at the freezing temperatures are of a dark brownish colour and I'm not sure which phase this could be along ice. Raman spectra also does not give a definitive answer. In case of a ternary, how do I know if I have antarcticite or hydrohalite, and which one melts at the temperature of initial melting? I'm still pretty new to this technique and do not have a lot of experience. Also, which program do you suggest for plotting my inclusion composition within a ternary diagram with drawn temperature isolines and drawn out fields of primary crystallization (in case if I do really have a ternary system) of the H2O-NaCl-CaCl2 system?
Many thanks in advance!
There are a lot of software for modeling vibrational spectra, but what is the best one? There are two major branch of software: firs principal (ab initio) and semi empirical. I'm interesting the both. The "best" means is the software gives the relevant result comparing with experimental spectra.
Question to blue and red shift during Raman spectroscopy of coesite:
For me, the significant blue shift of the coesite Raman lines is a mystery, and I cannot find a simple answer on the net. Therefore I have performed Raman measurements on an ideal SOS sample. This sample is characterized by an epitaxial Si layer on a single crystal wafer of sapphire (SOS).
I have taken Raman spectra of Si at different laser power from 10 to 100% of the 532 nm laser - 100% corresponds to 50 mW.
For the Si main line, I obtained a 520.1 ± 1.8 cm-1independents of the power. That means that the used laser power does not generate the blue shift in the coesite spectra, and the blue-red shift is generally reversible. Furthermore, the SOS test has shown that the problem does not come from a lousy device adjustment.
Water determination gives for coesite very high values of about 8500 ppm or more. Can the high OH-concentration be responsible for the blue shift? This high water content is only possible if the coesite is formed at very high pressure. Another possibility is a significant Al content in the coesite lattice (only possible at high pressure, similar to stishovite which can accommodate Al2O3and H2O through coupled substitution at pressures above 30 GPa (see Tschauner 2019)). For that spokes, the very strong 330 cm-1 bands in the Raman spectrum of coesite are generally missing in the “standard coesite.” All other essential lines of Coesite are present.
Tschauner, O. (2019) High-pressure minerals. Am. Miner. 104, 1701-1731
The problem is that I have a UPS spectrum like the one in the attached photo. This spectrum goes to zero near E=1.5 eV without having a step near this value. the nearest step is about 5 eV. Most of the information I found in literature deals with spectra goes to zero around zero eV but I didn't find anything related to my case.
Can I calculate the work function using the width of the spectrum? If not, what is the correct procedure to follow to calculate the work function and the ionization potential energy?
Thanx in advance.
Attached an example and how I tried to analyse it.