Quick Overview #
Certain peaks in XPS appear as asymmetric lineshapes due to shake-up effects. If we wish to peak model these, we need to know how to add asymmetric lineshapes in Avantage.
Creating an Asymmetric Peak #
After we add a peak, we can highlight/select the columns of the 4 parameters at the end of the peak table (LG Mix (%) Convolve, Tail Mix (%), Tail Height (%) and Tail Exponent, and right click to clear all constraints. If we then fit our peak to our asymmetric emission, we now see the lineshape morph to account for this peak asymmetry.
LG Mix (%) Convolve #
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This indicates the proportion of Lorentzian versus Gaussian character in the peak shape.
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A 100% Gaussian peak is purely symmetrical and typically used for instrumental broadening.
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A 100% Lorentzian peak is sharper and used to represent lifetime broadening (due to core hole lifetimes).
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For example, L/G Mix = 32.38%, meaning the peak is a mix, with ~32% Lorentzian and ~68% Gaussian.
Tail Mix % #
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Describes the proportion of the exponential tail included in the total peak shape.
- A higher tail mix suggests more asymmetric tailing of the peak.
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For example, Tail Mix = 62.89%, indicates significant asymmetry or tailing in the peak.
Tail Height % #
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Refers to the relative height of the tail portion of the peak.
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Usually compared to the peak height.
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For example, Tail Height = 0.00%, indicates that although the peak has a long tail (as per tail mix), the height at the tail’s start is very low (essentially zero).
Tail Exponent #
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This is a parameter that controls the decay rate of the tail.
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A smaller exponent means a slower decay (longer tail), while a larger exponent means a faster decay (shorter tail).
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For example, if the Tail Exponent is 0.0955, this means the tail decays slowly, contributing to significant tailing.
References #
- Islam, M. J., et al. (2020). “The effect of metal precursor on copper phase dispersion and nanoparticle formation for the catalytic transformations of furfural.” Applied Catalysis B: Environmental: 119062. Read it online here.
- Miller, A. and G. Simmons (1993). “Copper by XPS.” Surface Science Spectra 2(1): 55-60. Read it online here.
- Vasquez, R. (1998). “Cu2O by XPS.” Surface Science Spectra 5(4): 257-261. Read it online here.
- Vasquez, R. (1998). “CuO by XPS.” Surface Science Spectra 5(4): 262-266. Read it online here.
- Biesinger, M. C. (2017). “Advanced analysis of copper X‐ray photoelectron spectra.” Surface and interface analysis 49(13): 1325-1334. Read it online here.
- Thøgersen, A., et al. (2008). “An experimental study of charge distribution in crystalline and amorphous Si nanoclusters in thin silica films.” Journal of Applied Physics 103(2): 024308. Read it online here.
- Moretti, G. (1998). “Auger parameter and Wagner plot in the characterization of chemical states by X-ray photoelectron spectroscopy: a review.” Journal of Electron Spectroscopy and Related Phenomena 95(2-3): 95-144. Read it online here.
- Batista, J., et al. (2001). “On the structural characteristics of γ-alumina-supported Pd–Cu bimetallic catalysts.” Applied Catalysis A: General 217(1-2): 55-68. Read it online here.
- Ghijsen, Jacques, et al. “Electronic structure of Cu 2 O and CuO.” Physical Review B 38.16 (1988): 11322. Read it online here.
