Relative sensitivity factors are designed to scale the area (CPS eV) for any given photoemission line to permit the calculation of the amount-of-substance corresponding to a given element. Therefore, only one photoemission peak from each element is required to compute the atomic concentration for a sample. Si 2p is generally used for the contribution of silicon to the atomic concentration because chemical state for silicon is better resolved than Si 2s and, for elemental silicon, plasmon peaks from Si 2p appear beneath Si 2s increasing the uncertainty in background removal and integration limits used to computer Si 2s peak area compared to Si 2p.
Hi I have an In2O3 sample, the XPS survey spectra shows In 3s, 3p and 3d peaks and O 1s peak. Which In peak should I use to get the stoichiometry? When I used In 3d the result is way off!!
Quantification by XPS is challenging because the relationship between photoemission peak, as measured, depends on instrument and the nature of the sample. I would need to see a survey measurement and know more about the sample and instrument before being able to comment on how to understand stoichiometry as measured by XPS. Please send your data to neal@casaxps.com.
Hello! I have a vms file from a modified chitosan powders (organic material, I only see C, N and O) adquired with a Kratos Axis instrument. I want to know if is correct to apply the "C-H film" as a escape deph correction model to obtein the correct concentrations?
@@casaxpscasasoftware4605 Also, I am not sure about the transmission function to use for the data taken via scienta instrument. Is transmission function and escape depth correction already included in RSF value provided in the default library?
For historical reasons, the use of escape depth correction is not used in a standard way. For older instruments the KE dependence is sometimes used to compensate for other factors than escape depth. I would need to known more about your data to make an informed suggestion for the the best escape depth correction for your data. neal@casaxps.com
Si 2p is used to estimate the amount of silicon for two reason of which I am aware. Firstly, elemental silicon results in sharp plasmon loss peaks and these plasmon peaks from Si 2p include a plasmon peak beneath Si 2s. Hence the background beneath Si 2s is not always as simple to describe as Si 2p. Secondly, Si 2s is best described by a Lorentzian shape which extends beyond the point at which an inelastic scattered background responds to Si 2s photoemission. It is therefore harder to separate background intensity from primary photoemission for Si 2s even for the case of SiO2 which has a significant band gap. Quantification requires the matching of RSF to background for photoemission peaks and in general defining the background for Si 2p is easier than Si 2s.
I have CasaXPS Version 2.3 and I do not see the Escape Depth Correction part in the Sample ID Dialogue Window. Any idea on where I can find this? Instead there's just an option to "Update MFP Exponent" and enter a number for "MFP Exp.". Any help on how to properly account for escape depths in my version would be greatly appreciated.
Possibly related to this: in the Quantification Parameters Dialogue, there is no text below the checkbox for Automatic, the text field and the Update button. I.e. the "Escape D.C.: Non / ADC Angle = 60" text is missing.
Hi. thanks for the overview. why did you not take into account the Si 2s core level to determine the atomic percentage?
Relative sensitivity factors are designed to scale the area (CPS eV) for any given photoemission line to permit the calculation of the amount-of-substance corresponding to a given element. Therefore, only one photoemission peak from each element is required to compute the atomic concentration for a sample. Si 2p is generally used for the contribution of silicon to the atomic concentration because chemical state for silicon is better resolved than Si 2s and, for elemental silicon, plasmon peaks from Si 2p appear beneath Si 2s increasing the uncertainty in background removal and integration limits used to computer Si 2s peak area compared to Si 2p.
Hi I have an In2O3 sample, the XPS survey spectra shows In 3s, 3p and 3d peaks and O 1s peak. Which In peak should I use to get the stoichiometry? When I used In 3d the result is way off!!
Quantification by XPS is challenging because the relationship between photoemission peak, as measured, depends on instrument and the nature of the sample. I would need to see a survey measurement and know more about the sample and instrument before being able to comment on how to understand stoichiometry as measured by XPS. Please send your data to neal@casaxps.com.
Hello! I have a vms file from a modified chitosan powders (organic material, I only see C, N and O) adquired with a Kratos Axis instrument. I want to know if is correct to apply the "C-H film" as a escape deph correction model to obtein the correct concentrations?
I would need to see your spectra before I could make any comment about quantification of your sample. neal@casaxps.com
@@casaxpscasasoftware4605 Thank you, I will send you an email
Which library to use for the data taken via gamma data scienta instrument?
If you are using an Al or Mg anode X-ray source then the Scofield library used by default in CasaXPS is appropriate for Gamma Data Scienta spectra.
@@casaxpscasasoftware4605 Also, I am not sure about the transmission function to use for the data taken via scienta instrument. Is transmission function and escape depth correction already included in RSF value provided in the default library?
For my Work with Graphene oxide, the Escape D.C is always KE Exponent, should I change it to EAL?
For historical reasons, the use of escape depth correction is not used in a standard way. For older instruments the KE dependence is sometimes used to compensate for other factors than escape depth. I would need to known more about your data to make an informed suggestion for the the best escape depth correction for your data. neal@casaxps.com
@@casaxpscasasoftware4605 Thanx, I've already sent you an email
Hello! I want to know why Si 2s is not quantified in the calculation?
Si 2p is used to estimate the amount of silicon for two reason of which I am aware. Firstly, elemental silicon results in sharp plasmon loss peaks and these plasmon peaks from Si 2p include a plasmon peak beneath Si 2s. Hence the background beneath Si 2s is not always as simple to describe as Si 2p. Secondly, Si 2s is best described by a Lorentzian shape which extends beyond the point at which an inelastic scattered background responds to Si 2s photoemission. It is therefore harder to separate background intensity from primary photoemission for Si 2s even for the case of SiO2 which has a significant band gap. Quantification requires the matching of RSF to background for photoemission peaks and in general defining the background for Si 2p is easier than Si 2s.
I have CasaXPS Version 2.3 and I do not see the Escape Depth Correction part in the Sample ID Dialogue Window. Any idea on where I can find this? Instead there's just an option to "Update MFP Exponent" and enter a number for "MFP Exp.". Any help on how to properly account for escape depths in my version would be greatly appreciated.
Possibly related to this:
in the Quantification Parameters Dialogue, there is no text below the checkbox for Automatic, the text field and the Update button.
I.e. the "Escape D.C.: Non / ADC Angle = 60" text is missing.
CasaXPS 2.3.22 can be downloaded from www.casaxps.com/roscoff2019/video_list.htm. This version is soon to become the release version of CasaXPS.