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Hello,
I've recently come across different analytical techniques (EDS, FTIR, XPS etc...) that can be used to characterize surface, but I don't really know much about their advantages/disadvantages when it comes to surface characterization when comparing the to each other. Could you recommend me some good book or article on this topic?
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Thanks.
Then is there some books for 2D or 3D surface regression methods and their difference (advantages and disadvantages)
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I want to study about 2at% Mo dope of BiVO4, i first use Bi:V:Mo = 1:0.98:0.02 , but i didnt get what i need after XPS and EDS, I want to know how can i calculate to get 2 at% Mo dope BiVO4
My precursor are Bi(NO3)3·5H2O, NH4VO3 and Na₂MoO₄ ·2 H₂O.
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For analyzing and deconvoluting x-ray photoelectron spectroscopy (XPS) data, I use CasaXPS. Is there any such standard/recommended software for analyzing UPS spectra ?
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I used to do fitting with CASA XPS but now I am using a software from SPECS called Prodigy. I find it much better than CASAXPS.
Prodigy | SPECS (specs-group.com)
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As I know, photo electron from p,d,f... orbital can make similar peaks in XPS, but differ in size, caused by spin-orbital coupiling.
Now, I'm analysing my metal oxides sample with XPS.
my Ni scan shows two Ni2p1/2 Ni2p3/2 peak as expected, but their shape is different.
the later one has one or two more peak even at a glance.
so, my question is:
1) what can make this things happen?
2) which peak should I handle?
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Dear Kim, first of all, did you clean your sample prior to the xps measurements? An Oxidation of the metal surface may cause Ni-oxide peaks with related different binding energies, and thus you'll get multiple splitted peak groups, both for the underlying metal and the surface oxide…
coming to your original question, the FWHM as well as the other peak parameters (Gaussian /Lorentzian contribution and eventually the exponential tail in the case of metals) for spin-orbit splitted peaks such as 2p 1/2 and 3/2 are usually quite similar, you may want to have a look into surface science spectra (avs.citation.org) and see detailed peak analysis there. But, parameters do not need to be exactly the same, due to a slightly different energy of the splitted orbitals, also the transmission function of your spectrometer will slightly change, which may lead to very (!) small changes of the peak parameters. However with regard to your sample, I feel that the state of your sample is responsible for the different peak… hope this helps, Dirk
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The Pd thin film sample had a native oxide layer. The spectrum was recorded with Al Kα irradiation. I cant identify the origin of the sub-peak at ~1150eV (green line). From my understanding it cant be a plasmon peak as these are on the higher binding energy side and it cant be another Pd peak, as lower energy orbitals have higher binding energy as Al Kα can provide. Can it be another oxygen Auger peak? I cant find anything in the literature besides the O KLL peak...
Thanks!
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This is just the shape of the Pd MNN. Auger peaks are not like core level ones where you have a single symmetric (usually) peak. The shape of the auger peaks is generally complex and consists of many features. I suggest you'd have a look at this paper ( ), where you can see that the feature you're looking for is there even for the pristine metal. Moreover, the fitting you have performed is not accurate because the two peaks you have fitted are not due to the oxide, but are also present in the metal.
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Recently, the XPS instrument in our lab underwent repair and maintenance. The difference that I can find now is that I am unable to get a clear focus of my sample (when it is inside the analysis chamber) as I used to get earlier. This is degrading the quality of my plots with no clear peaks to be seen. Any troubleshooting suggestions would be highly appreciated!
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If you can't get any clear peaks, that sounds pretty much like a voltage issue, so either the analyzer energy or the retarding ratio might be not well-defined anymore. I suppose checking with a multimeter whether (a) a lens is short-circuited (can be done without venting) to grounding/other lenses or (b) all lenses are still contacted (requires venting).
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I have to analyse my Chitosan Cu nanocomposite sample through XPS. I need an idea about the energy of Ar+ ion and the time of sputtering if etching is done prior to XPS analysis.
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Dear Dr. Elbright Dillu ,
I suggest you to have a look at the following, interesting paper:
-Towards reliable X-ray photoelectron spectroscopy: Sputter-damage effects in transition metal borides, carbides, nitrides, and oxides
G.Greczynski,. L.Hultman
Applied Surface Science, Vol. 542, 148599 (2021)
My best regards, Pierluigi Traverso.
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How do apply the relative atomic sensitivity factors of C 1s and N 1s? what kind of values and relations can be obtained?
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this is the paper I was referring to:
hope this helps, Dirk
P.S. In an XPS experiment, you may calculate the concentration of C and N elements by using those cross sections. You'll also need the transmission function of your spectrometer etc.
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What does a charging shift represents in XPS data? How is this possible in sample?
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Charging usually happens for one of these reasons:
a) your whole substrate is insulating
b) your investigated film doesn't have enough contact to the substrate
(c) you didn't ground your sample properly)
In the first case, all peaks are shifted while in the second case only the film peaks are shifted. Since the ionization leaves behind a positive charge which is not compensated from the grounding, the binding energy of the remaining electrons increases.
Compensating this effect properly is rather hard, if there is no suitable reference within the system. You will find that quite a large fraction of the community still uses the somewhat arbitrary C1s correction, about that see
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Can any one help me by providing process details (pdf / video) to interpret the valance band XPS spectra.
I have obtained VB XPS data of NiO thin films. I would like to know the valance state of Ni in the NiO.
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How can one determine oxygen non-stoichiometry for ABO3 perovskites using XPS? Take for example, Ba0.5Sr0.5Co0.8Fe0.2O3-d. I will be glad if anyone could clearly and succinctly explain it. Thank you very much.
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What is the meaning of the C/O ratio in XPS analysis?
For example, Sample 1 's C/O ratio is 3 and Sample 2 's C/O ratio is 4.
then, What can I get from this difference?
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It will give you the molar ratio, but you have to take in account instrument parameters. Best to use the software. Either way, you have more oxygen atoms in the second sample.
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I am currently working on characterizing Pd(111) using XPS but I keep getting a low electron count( Intensity)
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If you have a count rate from a previus sample to look at and condifent that the counts are lower then could be any of the following for example - some will be system dependent for example:
1. Sample very dirty so attenuating the Pd peaks
2. X-ray power lower than before
3. Position of sample relative to x-rays and analyser
4. Channel plates/Channeltron needs replacin or at very least plateaued again
5. Wrong slot/aparture used giving small spot analysis
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1. Is it possible to multiple peak fit O 1s spectra of the XPS in case of high entropy alloy.
2. The peak identification, is it possible since most of the metal oxide peaks are within a very narrow range in the O 1s spectra.
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I would recommend checking how wide an O1s peak is for a less complicated compound with your XPS setup. If your alloy has a wider peak, you can put in components at the positions of the individual metal oxides and see if that's a proper reconstruction or whether you need more, eventually mixed, components.
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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.
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From O 1s spectra alone, it is very difficult to find which metal is forming oxides because binding energy values are very close for metal oxides. But you can analyse the high-resolution XPS spectra of each metal present in your sample. This will definitely help you find out which one is forming oxides.
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I am performing XPS analyses of a sample consisting of B, N, and C. I see that there is around a ~5eV charge difference in C1s peak. But applying a 5eV correction is disturbing the peaks of other elements to a considerable extent. Any help will be highly appreciated.
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Especially when your sample contains carbon, you will 100% generate false binding energies with it since there is surely a different carbon species than "generic adventitious carbon species".
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I'm using XPS these days to analyze a set of nanomaterials that I am synthesizing. I'm getting familiar with the Avantage data processing tool that is installed on the computer attached to the XPS instrument. For learning the processing tool at my pace, I wanted to know if I can install it on my personal computer. Suggestions will be highly appreciated.
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For proper deconvolution of XPS peaks use origin software. It is free for 7 days trial.
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I have XPS data and want to know how to determine whether the oxides are FeO type or Fe2O3 type or etc.
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Ashwani Ashwani My experience of such systems is that the surface (top 10 - 15 atomic layers maximum) is always fully oxidized (.i.e. all would be Fe3+ in your system from peak shift). The bulk Fe2+ can only be shown by (say) Ar+ etching of the surface to remove the top layers (including C) and get into the bulk composition.
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I am analysing the XPS spectra of TiN thin films. I tried the binding energy scale referencing using C 1s peak of adventitious carbon, but it is not reliable as it may lead to unphysical results (according to some reported literature). Is anyone suggest to me the best method for the same?
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You can calibrate to the N1s peak whihc should be 397.1 eV (see D. Jaeger, J. Patscheider, J. Electron Spectrosc. Relat. Phenom. 185 (2012) 523-534)
I will say this, don't get tied down by the C1s referencing issue that has come around agian (it does every 5 to 10 years or so!). Whilst C1s referencing is probably wrong, it is a convenint method and you can think of the binidng energies you see as relative to this, just be appreciative of the sample history and how handled etc.
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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.
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Dontt forget that the X-ray induced Auger will have a different information depth to the C1s core level, so depending on how 'clean' your sample is from the reduction of GO may be more sensitive to the surface carbon. However to comment more it would be good to see the C1s and O1s spectra to comment on the values
See my recent paper discussing some analysis of carbon linked below
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I am beginner at XPS and I don´t really understand the theory behind why the FWHM should be the same for doublet peaks.
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Although what Jürgen Weippert says is usually true, there are some exceptions
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I am fitting a W4d orbital where the 5/2 peak height appears to be smaller than the 3/2. I have tried with multiple curve fittings but the FWHMs are very high, between 4 and 6 eV. When using smaller FWHM, the peaks go too high and the resulting curve fluctuates too much in comparison to the raw data.
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4-6eV is indeed a lot, with a modern setup the expectation would be somewhere in the 1-2eV range. Are you allowed to share a spectrum so we can see whether it looks maybe like multiple components convolutiong into one thing?
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Dear Accademia, I received the PDT and SPE files of the XPS results, but I couldn't open any of them. Please suggest the possible software opening these files?
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For PDT files You need a suitable software like InkWriter/Note Taker to open them. Next, you may also analyze them on-line:
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Do you think that a home microwave oven can be used to eliminate moisture from a soil sample for FTIR analysis or XPS? If so, how many minutes should be used for a complete elimination?
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Dear Javier Ernesto Vilaso Cadre,
For elimination of soil moisture, it must be careful about thermal decomposition of organic matter such as carboxylic and phenolic functional groups of the humic acids, fulvic acids and hydrocarbon compounds which are decomposed in 170-300˚C. Moreover, carbon oxidation of the organic matter is occurred in 360-460˚C. Therefore, it is better to het the soil in oven at 100 ˚C for 48 h.
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Why is the satellite peak visible in the Cu2+ but not in Cu0?
The photoexcitation on the Cu site can lead to two final states, i.e. one: where after the creation of the 2p core hole the ground state configuration 3d9L is left roughly intact, second: where after the core hole creation one electron is transferred from the shell L into d state(3d10L-1). Latter one usually applies to the main photoelectron line.
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As I said, it would not be the same because the valence orbitals involved in the process would not have the same energies. In the case of Cu2+, the process is additionally facilitated by Ligand-Metal Charge transfer (LMCT) processes:
The position of the ligand in the spectrochemical series may further affect the shake-up shift energy since there are strongly and weakly splitting ligands.
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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?
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This depends on the material you are looking at. Let's take silicon as an example. For n-doped silicon, the binding energy of the valence band onset will be higher than for p-doped silicon (neglecting surface states). If you know the bandgap, you can determine the Fermi-level position within it. But keep in mind that this is only valid if your samples are conductive enough so that there is no charging.
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So, I am predicting the XPS spectrum of a molecule in Gaussian but I am not sure about the procedure. After optimizing the molecule I wrote the following keywords in the route section
# b3lyp/3-21g nonsymm guess=save geom=connectivity pop=full
I understood that the keyword: "pop=full" will provide the canonical orbital energies in the out file...however, I cannot find the energy associated to each atom in the text. For instance, Atom 1 -> C 1s = .....Hartrees
I have attached my log file
Any suggestion?
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That's not how orbitals work, when you perform DFT calculations, the electrons don't know what they are. They only "know" they have a certain energy and that they have certain localization probabilities.
Therefore, when you want to associate an orbital as "this has mostly C1s character", the most convenient way is to look at the orbitals with a viewer. There are several options, e.g. JMOL would be free to use. You will notice that core orbitals are well-separated by type, so once you know it for one carbon atom, you know the range.
You will notice that the orbital energies have a more or less constant offset from the "real" range. Therefore it is recommendable to either check whether someone has already used this functional+basis set calculation and reported the offset or alternatively calculate a substance for which you can determine the offset exactly.
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Hi, I am a beginner in this subject, but as I understood it is possible to predict (with certain accuracy) the XPS spectra of an organic molecule using NBO package from GAUSSIAN 09
My question is, in the output or chk file, where can I find the full X (eV) and Y values (Intensity in a.u.), so that I can trace the theoretical curve, for example of the C 1s?. I know where the Binding Energies of each atom can be calculated, but not the hole range of the spectrum.
For instance, using GaussView I visually locate the HOMO and LUMO of C15 (for example), but I wonder where is this important imformation located in the out or chk file
Thanks
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While I don't see why you would use the NBO package since you don't need bond orders for XPS analysis, you can get to an interpretation from your canonical orbital energies:
Extract the C1s area of your orbital energy file and check their distribution. Then you have the relative shifts of your components within the molecule. Since you don't have effects of a conduction process going on as it would be in graphite, you can "simulate" a primitive XPS by just putting a Lorentzian/Gaussian/pseudo-Voigt over it and play with the width of it; a former colleaugue of mine used a simple Linux shell script for that, but that was for Turbomole output files, so not helpful for you. Please note that depending on the used functional and basis set, there will be an offset on your absolute values.
On a Koopmans' Theorem level, you are done at this point.
If you want a bit more physics to be accounted for in your intensities, the "final state" or "frozen orbital" approximation would be the next level of escalation:
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How do I should do to determine the energy band of superlattice? I want to determine the valence band offset of the superlattice .However, I am confused the methods to determine the valence band offset. What I know is that valence band offset can be derived by XPS, electronegativity, but I am still confused of determining the superlattice energy band ,including the valence band energy , condunciton band energy.
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I assume you have a vertical superlattice arrangement, right? Because if you could somehow access the lattice layers from sideways, you might be able to access them with STS. But of course when you have it vertically, you would have to make a section and that often goes with the generation of new states in the cleaving or cutting region.
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Dear all,
we characterised a new synthesis of MoS2 with XPS and obtained the following results for Mo3d and S2p. From the spectra and according to Article Structure of Amorphous MoS3 it looks like MoS3, however, I think one can not clearly differentiate this from MoS2+elemental S only from XPS, or can one? Is there any other technique which could differentiate this?
Kind regards.
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Dear all,
I am also facing same thing, why Mo(5+) is showing 5+ oxidation state, there is any possiblity of defects due to sulphur like MoS3. if anyone knows kindly help and share reference.
thanks
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Recently I've got the XPS scans of my carbon materials (raw and processed with a laser). The interesting point is that I clearly see the CC bond shift after the processing (Or splitting the sp2 peak into sp2 and sp1?) from 284.8 to 283.7 eV in a couple with high conductivity. Do you have any thoughts: can this shift be connected with the inducing of graphitic- or graphene-like structure in situ? Charge compensation was applied for both samples.
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Is it only the C-C C 1s peak that shifts? If you modify surface conductivity by laser treatment the charge balance at the surface will be affected. It may happen that the surface is overcompensated resulting in that all peaks are shifted to too low BE.
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What is the significance of valence band spectra obtained using XPS? What are the parameters we can discuss about it in a manuscript. How can we analyze the data?
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Jürgen: The question was specifically aimed at VB spectra in XPS, not UPS or PES.
Shohaib: There is not much use for the VB spectra obtained by XPS, since it is not a proper method due to its low resolution, cross sections, and surface specificity, needed for VB analysis. In some cases, you can use it as a secondary qualitative descriptor, provided you are comparing spectra in which VBs differ significantly. You can also sometimes use it for surface charge compensation if there is no better way (e.g. reliable C 1s reference peak) and if the measured sample has filled states near Fermi level.
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Because Fe2O3, CuO, and MnO have satellite peaks in different positions.
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Please see my answers to this question:
Building on the material posted and linked there: the fact that the satellites are in different distances is due to the fact that the absorbing electronic states have different characteristic energies.
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I would like to know the oxidation state of a transition metal oxide nanoparticle, what is a good choice of substrate for that purpose?
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In addition to what Jürgen Weippert said, I would also check for potential overlaps of the photoelectric peaks of the substrate and the transition metal. Gold, platinum and the other noble metals have many xps peaks in almost any energy range, and the transition metal oxides show extended x-ray excited auger transitions which may overlap. Thus I feel that carbon might be the best opportunity. Best regards, Dirk
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If I deposit any insulating layer on top of perovskite layer in perovskite solar cell devices, which experiments can help me to find out the chemical bonds in between the perovskite and the insulating layer? Few literatures suggest XPS. What else can i use?
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Tamanna Mariam I guess you can use FTIR, Raman and NMR to corroborate your XPS results.
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I want data about xray diffraction, ultraviolet visible spectroscopy and scanning electron microscopy for my research thesis.
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Also check please the following very good link: https://www.toray-research.co.jp/en/technicaldata/techniques.html
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I collected XPS data for (Fe80Ga20 )88 B12thin films and targets on fused silica substrates.
On quantification the obtained data is too much varied from the expected quantification.
And I identified the issue is related to the Boron peak fitting.
Si2s plasmon loss feature overlaps the Boron peak.
My XPS plot is also attached for your reference.
So my question is
  • How to fit Boron peak from the plasmon loss feature ?
Thanks in advance.
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OK, that's a quite low and noisy signal. I would not apply anything sophisticated here, just a primitive linear or Shirley background subtraction and fitting with two simple Gaussians (check plausibility by eyeball) should do the job. Getting into Voigt/pseudo-Voigt/whatever-special-territory wouldn't lead to a lot more accuracy, I guess.
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Nickel nanoparticles were prepared, and when preparing nickel chloride was used in addition to hydrazine and other materials
When examining the obtained nanoparticles by XPS , chlorine and nitrogen appeared on the surface of nickel NPs.
what does that mean??
#chemistry
#nanoparticles
#nickel_nanoparticles
#nickel
#XPS
#X-ray_photoelectron_spectroscopy
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Sorry I'm late to the party.
I had seen similar things when preparing supported Pd and Pd alloy catalysts back in the 1970's from chloride precursors and hydrazine hydrate reduction. Intractable chlorine species is left on the support (most likely) or associated with the metal. I do not believe that this is due to inadequate reduction as the species is not removed by multiple washing in DI water. Attempts to make 5% loaded catalysts invariably led to final amounts around 4.5% and I suspect that this was due to removal in the washing stage of the additional metal by reduction in the liquid outside. You could try H2 reduction as an alternative. Intractable N was also present especially in systems with nitrate precursors (as expected!).
These species are easily seen in XPS as they're pulled to the surface by chemisorption induce segregation and thus minimization of Gibbs Free Energy.
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How to analyze and interpret XPS data for charge state determination? what other results can we get from it? If a compound is doped by replacing one element by other, then in XPS data we get the content of dopant as 33% or 45%. May I know with respect what this content is? As being dopant this much cannot be the concentration of dopant in whole compound.
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The main point I would make is that XPS is a surface sensitive technique. As such, 5 - 10 atomic layers would typically be examined. This is not a bulk composition (as 33% or 45% may suggest). You will find the surface to be full of fully-oxidized species and carbon (often the C 1s peak at 285 eV is used for 'charge correction' but this is somewhat controversial these days). Further, the surface will be enriched in those species which will be pulled to the surface with chemisorption enriched segregation and minimization of Gibbs Free Energy. As a good example, in PdAu systems we invariably find enrichment of Pd on the surface in comparison to the bulk composition. Ar+ etching may be needed to probe below the surface into the bulk composition. I would hesitate to call a composition of 33 or 45% of a species to be 'doping'. Doping may only change the XRD pattern slightly - 33 or 45% will almost certainly mean significant changes to the lattice constants. If you want the content of species (and the chemistry - which you do not state is vital) I'd be removing the materials (say with acid or aqua regia) and then analyzing with AAS or ICP.
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So I am working on Cobalt and i have the XPS data as i want to know the oxidation states. but i am not able to differentiate that whether it is Co(III) or Co(II)
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In order to distinguish between Co2+ and Co3+ I would go back to the early days of ESCA/XPS (which everybody forgets). Take appropriate Co2+ and Co3+ salts and run them in your XPS system. This will give you a good feel of what to expect. You can then vary the system somewhat without changing the character by absorbing the salts on an oxide such as silica and then looking at the new spectra. In this way you may be able to begin to understand your system. Good luck with your research.
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I have been asked to use the 284.8eV peak in the C1s narrow scan as the reference peak for fitting all other potential peaks for a carbon material. Also, which fitting optimization parameters yield the mixed Donjiach-Sunjik, simplex sum or Powel sum? Thank you in advance
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I fully agree with Jürgen Weippert
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Elaborate keeping in view of XPS
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Zn 2p describes one of the core levels of the zinc atom, corresponding to a 2p orbital. There are others, like the 2s, 3s, 3p, 3d etc.
There is no such thing as a 2d orbital.
Due to spin orbit coupling, the 2p core level splits up into 2 levels with different binding energies, reffered to as 2p1/2 and 2p3/2.
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If we have XRD results of the synthesized materials and other characterizations (XPS, transient spectra, Raman spectra and Adsorption and fluorescence band shapes etc) results calculated from theoretical software like ORCA. Is it valid approach for research article publication or not? If valid, What is the impact of this approach? in comparison with experimental results.
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If you are able to show the practical (experimental) data and the predicted (theoretical) data then that is perfect. Remember a model helps understand data in a theoretical point of view while experiments give the practicality of your work which means the two cannot be separated as they both validate your work.
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As a result of α--Fe2O3 and γ--Fe2O3 peak positions being similar
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Dear Sujit,
iron ions are only located in octahedral sites in the corundum structure of hematite (alpha-Fe2O3). Irons ions are located on both octahedral and tetrahedral sites of the spinel structure of maghemite (gamma Fe2O3).
Best regards.
Philippe.
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Hi all,
I have prepared Pd supported heterogenous catalyst by liquid media assisted reduction method. From the XPS it was observed that the surface is composed of both Pd+2 (as the major species, ~65%) as well as Pd(0). However, in XRD, the Pd+2 peak is not prominent and the intensity is very less compared to the Pd(0) peak intensity, although Pd+2 % is very high. Why it is so?
Thanks in advance...
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In addition to the excellent answers provided by Gerhard Martens and Yuri Mirgorod I would also examine what is measured by XPS and XRD in terns of penetration gap and the type of catalyst (I worked with such catalysts in my Ph.D when dinosaurs ruled the earth with both XRD and XPS - indeed the 7th ESCA/XPS system in the world...). In XPS you're looking at maybe the top surface 10 - 15 atomic layers only which is invariably fully oxidized and thus Pd2+ will show strongly from the shift in eV. You'll only start to 'see' the bulk if you (for example) argon ion etch the system. With XRD (dependent on the sample and element) you'll have a great deal more penetration (perhaps, in theory, up to a micron or more). In this latter case you'll see more of the bulk Pd0 metal. In XRD you can distinguish the lattice spacing of Pd from PdO (as Gerhard Martens states) and not the oxidation states. One other technique that would be extremely valuable to you is TPR (Temperature Programmed Reduction). If you have the ability to reduce the system (by hydrogen) in your XPS set up then you'll easily be able to remove the oxide and see the Pd metal reflections only.
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All XPS takes C1s reference to analyze the sample but Adventitious carbon is in general an unknown compound, not an inherent part of the sample, does not make proper electrical contact to the analyzed sample, binding energy of the C 1s peak varies in a wide range.
What are the alternative methods?
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I believe you would find good discussion on this XPS challenge in the following paper:
As it is mentioned in this review paper, you can consider calibration based on Fermi level. However, it depends on your material if it shows such a level (insulators most likely not compared to conductive materials).
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I have synthesized Fluorine-doped Carbon dots and found XPS for semi-ionic and ionic C-F bonds. How can I conclude these data? Thanks in advance.
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Thank you, sir. Yes, ammonium fluoride is the precursor for CDs synthesis. Ionic fluoride is cleared.
But, can semi ionic fluoride bond may form?
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Hi Friends,
Can anybody from this platform explain the reason, why hydrogen and helium are not possible to detect by XPS?
Thanks and Regards
ANSARI P
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XPS works with core electrons of atoms and the only shell that H and He have is the valence shell. Therefore all states that are due to the presence of H or He will be very close to the Fermi edge and that's the place where XPS has only very low cross sections.
If you use UPS which is more suitable for the Fermi-VB region you will of course receive signals that are due to the presence of H or He.
In the case of hydrogen, these will be a sigma bond orbital signal unless you happen to investigate ionic hydrides (or atomic hydrogen in the gas phase for the sake of completion). Therefore the approximations that are made in the equations for stoichiometry determination are no longer valid.
In the case of helium, you can of course get a UPS signal but unless you do special things (e.g. ) that would not be very informative.
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I am doing research in water-splitting/OER/HER applications, recently encounter the problems of explaining XPS shift resluts. I thought that when XPS shifts to higher binding energy, it means that the valence number of the atom is increased, and whether the performace will be better depends on different applications. But someome told me that if the XPS shifts to lower binding energy, the performance is usually better. Is it true? Thanks for answering.
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@Sourav Roy Thanks for your kindly reply!
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for analyzing the peaks of Cu, Zn and O under X-ray photoluminescence analysis
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Jürgen Weippert thank you for your suggestions...
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Many people use both side adhesive conducting carbon tape as conducting electrode especially in PVDF based flexible nanogenerators. This tape is also extensively used in SEM, EDS, XPS etc. We tried to check (by using multimeter) whether the two sides of this tape conducts or not and found no conducting nature. We also tried to check this thing by affixing two aluminium foil on the two sides of the both side adhesive carbon tape. But in this case also, we found no conducting nature between the two aluminium foil. We also applied pressure and electric field (~ 100 V) across this system during checking the conducting nature through multimeter. But, in this case also same result appeared. Why is it happening? How is it useful for the purpose mentioned above?
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Personally, I support Saurabh Singh has very well explained the impact w.r.t. the examination intended of samples.
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I looking forward to know how to specify the band gap alignment and band offsets of two layers 2D heterostructure semiconductor?
Can I determine the band alignment (type I or II) without using XPS or STM?
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I agree with Valentin Bogatu.
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I made defective TiO2 with Oxygen vacancies and I noticed the O 1s peak shifts to lower binding energy compared to the pristine TiO2. How Can I explain that?
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You have to address these points:
1. Does the Ti2p also shift? If so its a charging issue - recalibrate your data to the Ti2p3/2 peak at 458.5 eV
2. How does XPS detect oxygen vacancies? A vacancy WILL NOT give a O1s signal, instead the lattice oxide peak will broaden - anyone assigning a high binding energy peak is an oxygen vacnacy is just wrong
3. If the samples are air handled, then you are very unlikely to have oxygen vacancies anyway as oxygen/water from the atmosphere will fill these gaps
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It's known that some people either students or researchers ask me to do an energy correction to C1s signal their spectrums; and that's something I usually do but in some cases it's not that easy to do since the C1s spectrum appears with multiple peaks as the example I attach in here. So, what should I take in consideration in order to properly choose the right peak to shift the signal to? I tend to choose the very first peak (from right to left) no matter it's not the tallest one, but my doubt is if I'm doing it right or am I wrong in doing it that way.
Thanks in advance.
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Thanks Jhonatan Rodriguez-Pereira & Jürgen Weippert for your comments. Now I'll take homework to read this long weekend.
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I'm trying to figure out the origin shake up satellite features that are seen in transition metal oxides. From what I understand the shake up features originate when the ejected core electron excites a valance electron and the KE of of the core electron reduces as a result of the excitation. I found the following in "Core Level Spectroscopy" by DeGroot; "The satellite was first considered to be caused by the shake-up transition between the metal 3d and 4s orbitals, but it is now well established that it originates from the charge transfer between the ligand 2p and metal 3d orbitals. I'm a bit confused on connecting the definition of a shake-up feature with what is said by DeGroot. Does it mean the electrons that are shared by the ligand 2p and 3d gets excited by the ejected core electron that give rise to the shake-up satellite? And can we assume that one reason to see shake-up satellite peaks in 3p energy range are the shared electrons between 3p and 3d orbitals?
Thanks in advance!
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Here are the general definitions of shake-processes (https://public.wsu.edu/~scudiero/documents/571-XPS-Lecture2_003.pdf):
Shake-up:The outgoing electron interacts with a valence electron and excites it (shakes it up) to a higher energy level. As a consequence the energy core electron is reduced and a satellite structure appears a few eV below (KE scale) the core level position.
Shake-off:The valence electron is ejected from the ion completely (to the continuum). Appears as a broadening of the core level peak or contribute to the inelastic background.
Therefore, the electron that takes the shake-up-causing energy does not have to be strongly correlated with the ionized core atom.
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I've been using thermal annealing to get thin films of mixed phase copper oxides and use the 2p feature of XPS spectra to characterized the Cu oxidation state. However, I observe a high energy doublet feature at 85 and 93 eV near the Cu 3p edge (image attached). This feature grows as I increase the annealing temperature and is very prominent when the Cu thin films is annealed at 400 C to get CuO. The Cu films are ebeam deposited on a SiO2 thermal wafer and then annealed in a tube furnace. Lack of the high energy feature at low annealing temperatures rule out possible contamination in Cu. Does anyone know what this feature is?
Thanks in advance.
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For Cu2p, a satellite 9eV higher than the main signal would be normal for Cu2+:
I don't have a reference that describes the same effect for Cu3p, but maybe it's the same shake-up and maybe the second peak is the next excitation?
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Dear Colleagues,
If I want to get the binding energy of each electron of an Atom, it it possible to get?
For example, I am getting BE of 3S electron of Cu to be around 960 eV. But, I want to get the BE of 1S electrons.
Please suggest, how to get this.
Thanks and Regards
N Das
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Respected Jürgen Weippert,
I get nice ideas from you. Please give some ideas about the energy of X rays normally used in XPS analysis in Universities. I am new in this field of XPS analysis.
Regards
N Das
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Hi all,
I have prepared some biomass-based activated carbon samples which are powdered in nature. To analyze for XPS, I had prepared the slides by dispersing the sample in ethanol and drop cast on to Si wafer. However, once it dried, the sample was coming out of the surface and unable to process further to complete the analysis. Can anybody suggest a suitable method to prepare the slides for XPS, especially for these kinds of powdered activated carbon samples?
Thanks in advance.
ANSARI P
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Dear Shahid,
Can you please get the details of Ag paste based sample preparation protocol? Also, is there any specific details which I need to be considered while purchasing Ag paste?
Thanking you in advance...
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I am looking to find a material (any type) that can offer me CO formation energy (> 2.0 eV) and NO formation energy ( < 0.5 eV) simultaneously. Secondly, how to confirm these formation energies experimentally? Your expert opinion in surface reaction, catalysis would be appreciated. Thanks
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Thank you Professor Frank T. Edelmann for the great insight. sure, I'll go through the mention linked. well, from your expertise, will you please suggest some potential materials which can show desired chemistry. Thanks
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I want to perform quantitative analysis for my XPS spectrum using curve fitting approach. I'm Mac user, can anybody recommend me any free source XPS software which can also process .txt files (I have raw data in .txt format).
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Theoretically:
From XRD patterns as follows:
Variations in the height of the specimen in its holder, whether increasing or decreasing, cause XRD peaks to change from their original location.
Important and useful pathways are connected to the XRD Curve:
Scherrer’s equation:
Particle Size, D = (0.9 x λ)/ (d cosθ)
λ = 1.54060 Å (in the case of CuKa1) so, 0.9 x λ = 1.38654
Θ = 2θ/2 (in the example = 20/2)
d = the full width at half maximum intensity of the peak (in Rad) – you can calculate it using Origin software.
To convert from angle to rad
Rad = (22 x angle) / (7 x 180) = angle x 0.01746
Example: if d = 0.5 angle (θ)
= (22 x 0.5)/ (7x 180) = 0.00873 rad
Then
Delta=1/D^2
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We need to characterize few organomettalic nanocomposite materials by XPS analyisis.
Is there is any lab in India where XPS characterization can be done on payment basis?
Thanks
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BITS Pilani Hyderabad,@ XPS facility is available.
Address: Central Analytical Laboratory,
Room. B-108, Block-B,
C/o. Prof. Ramakrishnan Ganesan,
Department of Chemistry,
BITS Pilani Hyderabad Campus,
Jawahar Nagar, Kapra Mandal.
Hyderabad - 500078
Telangana State
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Is there a method to find the coverage (in terms of monolayer) of organic molecules on metals surfaces? I am dosing my molecule on a Cu(110) surface with different deposition times and I am interested in finding the time corresponding to a monolayer coverage.
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Dear Paul Schweer in addition to the expert answers provided by Jérôme Lasne and Jürgen Weippert (I do not call myself an expert in this field) I would like to suggest to you the following potentially useful article:
Determining Surface Coverage of Self-Assembled Monolayers on Gold Electrodes
This paper has been posted by the author as public full text on RG. Thus is can be freely downloaded as pdf file.
Good luck with your work and best wishes!
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C1s peak at 284.8 corresponding to Adventitious Carbon is a reference for the X-ray photoelectron spectroscopy (XPS. However, when using carbon-based support, say Vulcan carbon (rich in graphitic carbon), r-GO and GO for deposition of active catalyst.
The C1s peak in these cases will be dominated by sp2 carbons, not by Adventitious Carbon.
How to calibrate the XPS data in that case?
How to account for the charging problem?
Thanks in advance
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As Jurgen states, the vulcan carbon should have enough conductivity. If using a monochromatic XPS system then analyse without the charge neutraliser on and ensure the carbon is in contact with the spectrometer (e.g. pressed in to a metallic well on the sample bar), then you shouldn't have an issue. The sp2 carbon will be ~ 284.5 eV depending on how well your spectrometer is calibrated.
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What are the reasons of chemical shift of C1s and N 1s in XPS, why the peak positions of the pure g-C3N4 and the modified g-C3N4 are different. 
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Technique which shows type of doping. Can we employ XPS technique. If yes please explain how?
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I agree with one of previous comment, question is to general. In my opinion the best and fast technique to check the type of doping is C-V (capacitance - voltage) type of measurements.
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I am using ceria powders but the XPS results shows me a high carbon content in reference ceria powder without adding any additives. When I used some additives containing carboxyl group in ceria , I could not differentiate the peaks in XPS spectra after deconvolution. C1s peaks for with and without additives looks same. How to differentiate the C=O due to CO2 or C=O due to COOH?
Also, I want to understand the type of bonding ceria has with different additives from XPS results. Can anyone suggest me how to resolve these issues?
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Why would you have CO2 (a gas) in the samples in XPS? If you truly has CO2 (even trapped in a matrix), then it would have a high binding energy of ~ 293 eV!
You can see organic C=O or COOH funcitons - C(1s) energies of roughly 286-287 and 288-289 eV respectively
Your concentrations may also be high as you are including the 4s peak from the ceria which sit in the same region as the C(1)s peak
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1. Whenever we deal with a material consist of silicon ( e.g. PDMS) for XPS analysis why do we use Si2p peak but not the nearby Si2s peak?
2. In general for materials like C, O we consider the innermost electron peak, that is C1s and O1s respectively but in the case of Si, it's Si2p. Why not Si 1s?
Thank you in advance.
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Dear Aum,
In general you would like to use the outer most orbital of the shell, 1s is the outer most orbital in the first shell and 2p is the outer most orbital in the second shell. The main reasons for this approach is:
  1. to avoid Coster-Kronig and Super Coster-Kronig effects, see for example Ohno, Jorunal of Electron Spectrsocpy and Related Phenomena, volumes 131-132 (2003) 3-28. These transitions effects the intensity, line with and introduce satellites in the spectra (Weightman, Rep. Prog. Phys., Vol. 45, 1982).
  2. The cross section for different orbitals and shells also determines the choice of core level to be measured. The cross section is in turn dependent upon the excitation energy used. The closer to the excitation energy the higher the intensity.
As Jhonatan Rodriguez-Pereira pointed out, The excitation energy also determine the possible states you can study. With 1487 eV photon energy as excitation energy for an Aluminum K-alpha source, most common in commercial XPS equipment, you can not access the Si 1s state which is located at about 1840 eV binding energy. If you use a higher excitation energy, e.g. using HAXPES instead of XPS you would go for the Si 1s, as the intensity for the 1s is higher than the 2p in these cases. HAXPES can be measured using synchrotron (as pointed out by Dirk Luetzenkirchen-Hecht) or using Ag L-alpha (about 3000 eV), Cr K-alpha (about 5000 eV) or Ga L-alpha (about 9000 eV).
Best regards,
John
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How do we judge the quality of charge compensation in high resolution XPS spectrum for a polymer sample ? should the peaks be in their right binding energy ?
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Charge corrections in XPS are a heavily debated topic. If you have some peak of whose correct position you are absolutely sure, that can help, but for a "new" sample that of course isn't the case.
Maybe start with this work here:
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It is know that XPS (X-ray Photoelectron Spectroscopy) gives elemental composition (what elements are present) and the chemical state/s (what other elements they are bonded to). I wish to know how XPS helps in knowing overall ''electronic structure'' and ''density of electronic states'' in the material being characterized.
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Aman Arora XPS characterizes the surface of a material rather than the bulk. The surface and the bulk of a material must be different in a mixture or in the presence of air or moisture.
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Through the articles and video I've seen in the quantification of elements by XPS survey of Si based materials, I noticed that only Si 2p is quantified. Why Si 2s is ignored?
Thanks for any reply.
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You can quantify on the Si(2s) instead of the the Si(2p) if desired as the area will be adjusted for the orbital sensitivity factor.
However to relate exactly to your question, if you quantified the Si(2s) AND the Si(2p) then you would be broadly doubling the amount of Si you have in your sample - so getting an eroneous result. Its the same for any element - you only quantify one (usually the most intense) set of peaks
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Can anyone please share or refer any good video links/notes/ppt/website related to the details of various composition analysis (e.g., XPS, XRF, EDAX etc.) carried out in nano-science & nano-technology? It'll certainly provide knowledge about why and when to use such tools or techniques & for which type of samples (e.g., thin films, powder, liquid etc.).
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If you are new to nano-based analyses. I would recommend you to start with online courses and get an idea about various characterizations. here is the link:
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The adventitious carbon located at 284.8 eV was used to calibrate the XPS raw data, which is an essential procedure before spectra analysis.
However, in the chemistry depth profile analysis, carbon features are nearly depleted after Ar+ etching treatment, so that the conventional energy scale calibration of XPS spectra using the adventitious carbon peak cannot be applied.
I found some investigations concluding that other elements, that specimen contains by itself, can be regarded as an internal standard for calibration [Li, Jerry Pui Ho, et al. Physical Chemistry Chemical Physics 21.40 (2019): 22351-22358.]. While I'm not sure whether this treatment is universally recommended?
My question is that could I use the adventitious carbon in a shallow depth to calibrate all the XPS spectra, including those which carbon signal (1Cs) is too weak to distinguish.
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Thank you all for your attention and constructive suggestions.
After I posted this question I subsequently took other internal elements as the benchmarks to correct my raw spectrum and got some tips. Here provides some feedback for any future discussion on this processing method.
My sample is a certain kind of high entropy alloy (HEA), containing five metal elements and also mixed with C and O on the very top surface. I'm concerned about the chemistry difference between the surface and inner bulk. When carbon is no longer sufficient for calibration, for example, I set the Fe dominating peak as a reference, the validity of this operation was considered by comparing the peak position of other metal elements with its reference value in the NIST database. The mismatch between the other four elements and its corresponding reference value is lower than 0.5 eV, which I think is a trustable way.
Of course, if one wants to improve the credibility, I also suggest conducting more than one calibrations based on different elements for those weak-carbon spectra. Specifically, Fe element for the first time and Cu element for the second time... The mismatch may get reduced.
Welcome for any further discussion on this point. Thx
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Assuming that we could probe using high enough energy XPS energy source,
How will be the binding energy of Au 2p3/2 will be different from the Au L3 absorption edge in XANES?
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It's simple just take a short look to this two techniques and pay attention to the mechanisms. In XANES the absorption of a monochromatic X-ray beam is probed as function of the X-ray energy. But In XPS one is analyzing the kinetic energy of the photoelectrons that are emitted due to the excitation by X-rays of well-defined energy.
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Starting from the bulk gold and going down to atomically precise metal cluster, we wanted to know how does the energy of excitation for 2p3/2 --> 5d transition will change with particle size
We have a range of atomically precise clusters say Au4, Au7, Au11, Au25 Au102, and Au nanoparticles of ~2 nm.
Thanking you
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Mr./Dr. Sharma, You need to first check Google and the RG also, before you put the query!
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How does the excitation energy of core energy levels (say 2p) to LUMO (or conduction band) of Au change with decreasing the particle size from bulk gold to nanoparticles and nanoclusters (<2nm) then to atomically precise clusters (say Au4).
Thanking you,
Yours
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I think chapter 4.1 of this dissertation from Berlin might be what you are looking for:
You can also check if the author has also published this in paper form.
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I want to calculate the atomic percentage from XPS.
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Thank You, Aman Gupta
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Hello colleagues!
Does anyone there know some certified XPS course/training, on-line preferentially?
I found one or two of them, but expensive...around USD 1.300 for 2 days.
Thanks!
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Hi,
You can choose from the following two ongoing courses:
Both edX and Coursera provide certification courses. You can always apply for Financial Assistance (provided at respective websites) for the reduction in course fee to earn a verified certificate.
Thanks
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typically, energy band diagrams need valance band (VB) and conduction band (CB). Eg has been calculated with the help of UV derived tauc plot. My question is how I do calculate VB using XPS data. As per my knowledge, VB is the direct value of binding energy. Please suggest.
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Please read this attached file.