1,442 research outputs found
Data for: Method to correct ambient pressure XPS for the distortion caused by the gas
No full textCross Section for N2 gas published as figure 2 in Sven Tougaard and Mark Greiner,"Method to correct ambient pressure XPS for the distortion caused by the gas"Applied Surface Science. (2020)First column: energy loss T in eVSecond column: the cross section K(T) in the form: IMFP*K(T) in units (1/eV) where IMFP is the inelastic mean free path and K(T)dT is the probability for the electron to lose energy in the interval T to T+ dT per unit path length travelled in the gas. It can be used with the QUASES software to correct XPS taken in a N2 gas for the distortions caused by the gas. IMFP*K(T) is the form used as input in the software
Improved depth information from routine analysis of the inelastic background of XPS and HAXPES spectra using optimized two‐ and three‐parameter cross‐sections
Full text linkDetermination of the depth distribution of complex nanostructures by X-ray photoelectron spectroscopy (XPS) inelastic background analysis may be complicated if the sample materials have widely different inelastic scattering cross-sections. It was recently demonstrated that this may be solved by using a mixture of cross-sections. This permits retrieval of depth distributions of complex stacks and deeply buried layers with a typical 5% accuracy. This requires however that the cross-sections of the individual sample materials are known which is often not the case and this can complicate practical use for routine analysis. In this paper, we explore to what extent a suitable two- or three-parameter cross-section can be defined independent of prior knowledge of the cross-sections involved but simply defined by fitting the cross-section parameters to the spectrum being analyzed. This paper presents a theoretical study following our recent paper that explored how to make the best choice of inelastic mean free path and inelastic scattering cross-section for the inelastic background analysis with the Quases-Tougaard software. It was previously shown that a rough analysis of the inelastic background could give a good idea of the depth distribution. Here, we demonstrate with model spectra from buried layers created with Quases-Tougaard Generate software that a rather accurate analysis can be performed for very different cases with an average ~5% error. This analysis is easy to apply as it only needs the two- or three-parameter cross-sections generated with the Quases-Tougaard software. This study is aimed to improve routine analysis of the inelastic background of XPS and hard X-ray photoelectron spectroscopy (HAXPES) spectra.</p
QUASES-Inelastic electron mean free path calculator (by TPP2M formula)
No full textThe QUASES-IMFP-TPP2M-CF software is a user friendly calculator for the inelastic electron mean free path for electrons in materials. It is based on the Tanuma, Powell and Penn algorithm [1] and has an option to account for relativistic effects [2].
The software includes a database with parameter values for all elements and a wide range of compounds, oxides, and polymers. There are also facilities to easily expand the database with new materials.
The software also provides means to calculate the elastic scattering correction in XPS. The change in XPS peak intensity from a layer of atoms at depth z, caused by elastic electron scattering, is conveniently described by a correction factor CF, which can be estimated with the software within two approximations [3,4,5]. For a practical application watch videos 6, 8 and 9 at: https://doi.org/10.5281/zenodo.5499741.
A manual is integrated in the software.
[1] S. Tanuma, C. J. Powell, D. R. Penn:Surf. Interf. Anal. 21(1994)165
[2] H. Shinotsuka, S. Tanuma, C. J. Powell, D. R. Penn: Surf. Interf. Anal. 47(2015)871
[3] A.Jablonski, S.Tougaard, 'Practical Correction Formula for Elastic Electron Scattering Effects in Attenuation of Auger and Photoelectrons',Surf. Interf. Anal. 26(1998)17
[4] Jablonski, S.Tougaard, Surf. Interf. Anal. 26(1998)374
[5] S. Tougaard, Practical guide to the use of backgrounds in quantitative XPS, J. Vac. Sci. Technol. A 39, 011201 (2021); https://doi.org/10.1116/6.0000661
Copyright (c) 2000-2022 All rights reserved
The software code is written by Sven Tougaard.
Copyright (c) 2000-2021 Quases-Tougaard Inc.
Free to use for non-commercial applications.
Sven Tougaard, Dept of Physics, Chemistry, and Pharmacy, University of Southern Denmark, DK-5230 Odense M, Denmar
QUEELS software for calculation of energy loss processes in TEELS, REELS, XPS, and AES including effects of the core hole
No full textQUEELS is for calculation of energy loss processes in TEELS, REELS, XPS, and AES including effects of the core hole
It is based on a dielectric response description of the interaction of the moving electron with the electrons of the solid and includes the boundary effects imposed by the particular experimental situation. Its validity has been verified in several experiments.
The QUEELS software can be downloaded at: doi: 10.5281/zenodo.6022426
QUEELS is free to use for non-commercial applications.
The software is based on theory published in the papers:
1. J. Lindhard, Kgl Danske Vid Selsk Mat-Fys Medd 28:8 (1954)
2. R H. Ritchie, Phys. Rev. 106, p. 874 (1957)
3. F. Yubero and S. Tougaard, Phys. Rev. B46, p. 2486, (1992)
4. F. Yubero, JM Sanz, B. Ramskov, S. Tougaard, Phys. Rev. B53, p. 9719,(1996)
5. AC. Simonsen, F. Yubero, S. Tougaard, Phys. Rev. B56, p. 1612, (1997)
A brief summary of the theory behind QUEELS and discussion of its practical application is published in the paper which can be downloaded here: :https://doi-org.proxy1-bib.sdu.dk/10.1002/sia.7095.
S. Tougaard, N. Pauly, F. Yubero, QUEELS: Software to calculate the energy loss processes in TEELS, REELS, XPS, and AES including effects of the core hole, Surf. Interf. Anal. 54, p. 820-833 (2022).
A brief users guide is available in the supplementary material to this paper.
The only input needed in QUEELS is the dielectric function of the material expressed by the so called energy loss function (ELF) as a sum of oscillators.
You may get acquainted with the software by reproducing the spectra shown in the guide and the abovementioned paper for Au and Si.
To do this, you first copy the files ELF_Au.txt and ELF_Si.txt into a folder e.g. C:\ELF\ELF_Au.txt. Then read the file with the "Set Material Parameters" menu in QUEELS.
ELF for a range of other materials can be found in:
Pauly, Nicolas, Yubero, Francisco, & Tougaard, Sven. (2022). ELF dielectric functions for various materials. (1.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.6024064
Copyright (c) 2001-2022 All rights reserved
QUEELS software is developed by Sven Tougaard and Francisco Yubero
Sven Tougaard, Dept of Physics, Chemistry, and Pharmacy, University of Southern Denmark, DK-5230 Odense M, Denmark
Francisco Yubero, Inst. de Ciencia de Materiales de Sevilla, Isla de la Cartuja, E-41092 Sevilla, Spain
(e-mails: [email protected] and [email protected]
QUEELS-XPS: Software to calculate the energy loss processes in XPS and AES including the effects of the core hole.
No full textXPS spectra consist of the primary photo-excited core electrons, including processes such as lifetime broadening, spin-orbit coupling, and multiplet splitting. On top of this, there is a background of energy-loss structures caused by excitations due to the sudden creation of the static core hole and due to electron transport out of the surface (including bulk and surface effects). The corresponding energy-loss processes are usually denoted ‘‘intrinsic’’ and ‘‘extrinsic’’ excitations. The QUEELS-XPS software calculates these effects quantitatively by a dielectric response description. It also applies to AES. The only input in the software is the dielectric function expressed by the energy loss function (ELF). The ELF for various materials is available at:
Pauly, Nicolas, Yubero, Francisco, & Tougaard, Sven. (2022). ELF dielectric functions for various materials. (1.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.6024064
The QUEELS-XPS software was first presented in the paper
Software package to calculate the effects of the core hole and surface excitations on XPS and AES
S. Tougaard and F. Yubero, Surface Interface Analysis 44, 1114-1118 (2012)
Note: The QUEELS-XPS software will be available here soon and can presently be downloaded at http://quases.com/products/queels-xps/
The QUEELS-XPS software is an extension of the QUEELS software which applies to EELS, REELS, AES, and XPS. QUEELS is presented in the paper "QUEELS: Software to calculate the energy loss processes in TEELS, REELS, XPS and AES including effects of the core hole"; by S. Tougaard, N. Pauly, F. Yubero, Surf. Interf Anal (2022) http://doi.org/10.1002/sia.7095. The QUEELS software can be downloaded here:
Tougaard, Sven, & Yubero, Francisco. (2022). QUEELS software for calculation of energy loss processes in TEELS, REELS, XPS, and AES including effects of the core hole (2.3). Zenodo. https://doi.org/10.5281/zenodo.6022426
Recent applications of QUEELS-XPS:
XPS primary excitation spectra of Zn 2p, Fe 2p, and Ce 3d from ZnO, α-Fe2O3, and CeO2
N. Pauly, F. Yubero, J.P. Espinós, S. Tougaard. Surface and Interface Analysis 51, 353-360 (2019) https://doi.org/10.1002/sia.6587
Quantitative analysis of Yb 4d photoelectron spectrum of metallic Yb
N. Pauly, F. Yubero, S. Tougaard, Surface and Interface Analysis 50, 1168-1173 (2018); https://doi.org/10.1002/sia.6402
Quantitative analysis of satellite structures in XPS spectra of gold and silver
N. Pauly, F. Yubero, S. Tougaard, Applied Surface Science 383, 317–323 (2016); http://dx.doi.org/10.1016/j.apsusc.2016.03.185
Quantitative analysis of Ni 2p photoemission in NiO and Ni diluted in a SiO2 matrix
N. Pauly, F. Yubero, F.J. García-García, S. Tougaard, Surf. Sci. 644, 46-52 (2016) http://dx.doi.org/10.1016/j.susc.2015.09.012
LMM Auger primary excitation spectra of copper
N. Pauly, S. Tougaard, F. Yubero, Surface Science 630, 294–299 (2014) http://dx.doi.org/10.1016/j.susc.2014.08.029
Modeling of X-ray photoelectron spectra: surface and core hole effects
N. Pauly, F. Yubero, S. Tougaard, Surface and Interface Analysis 46, 920-923 (2014) ; http://dx.doi.org/10.1002/sia.5372
Determination of the Cu 2p primary excitation spectra for Cu, Cu2O and CuO
N. Pauly, S. Tougaard, F. Yubero, Surface Science 620, 17-22 (2014); http://dx.doi.org/10.1016/j.susc.2013.10.009
Dielectric description of the angular dependence of the loss structure in core level photoemission
F. Yubero and S. Tougaard, J. Electron Spectroscopy and Related Phenomena 185 (2012) 552-5
Differential energy loss probability for 1000 eV electrons in N2 gas.
No full textDifferential Cross section for 1000 eV electrons in N2 gas determined in the paper:
"Method to correct ambient pressure XPS for the distortion caused by the gas"
by
SvenTougaard and Mark Greiner
published in Applied Surface Science 2020:
https://doi.org/10.1016/j.apsusc.2020.147243
Data structure:
Energy loss T (eV), IMFP*K(T) (eV^-1)
(where IMFP is the inelastic mean free path
Tutorial videos on the application of XPS inelastic background for characterization of composition and morphology of nano-structures with QUASES software
No full textThe tutorial videos illustrate the application of XPS inelastic background analysis for characterization of composition and morphology of nano-structures with QUASES software.
For an introduction to the method, see:
S. Tougaard "Practical guide to the use of backgrounds in quantitative XPS." J Vac Sci Technol A. 2021;39:011201. doi:10.1116/6.0000661
S. Tougaard "Accuracy of the non-destructive surface nanostructure quantification technique based on analysis of the XPS or AES peak shape". Surf Interface Anal. 1998;26(4):249-269. doi:https://doi-org.proxy1-bib.sdu.dk/10.1002/(SICI)1096-9918(199804)26:43.0.CO;2-A
The inelastic background analysis was done with the QUASES-Tougaard software . See www. quases.com.
It is recommended to read first the short description in the pdf file: Guide to the 14 posted videos.pdf. This explains briefly the purpose of each video.
To best understand what is done in Video 9 ("9.Practical procedure to correct for elastic electron scattering.mp4") you should first watch Video 8, then Video 6 and then Video 9
Sample-morphology effects on x-ray photoelectron peak intensities
Full text linkThe authors have used the National Institute of Standards and Technology Database for the Simulation of Electron Spectra for Surface Analysis to simulate photoelectron spectra from the four sample morphologies considered by Tougaard [J. Vac. Sci. Technol. A 14, 1415 (1996)]. These simulations were performed for two classes of materials, two instrument configurations, and two conditions, one in which elastic scattering is neglected (corresponding to the Tougaard results) and the other in which it is included. The authors considered the Cu/Au morphologies analyzed by Tougaard and similar SiO 2/Si morphologies since elastic-scattering effects are expected to be smaller in the latter materials than the former materials. Film thicknesses in the simulations were adjusted in each case to give essentially the same chosen Cu 2p 3/2 or O 1s peak intensity. Film thicknesses with elastic scattering switched on were systematically less than those with elastic scattering switched off by up to about 25% for the Cu/Au morphologies and up to about 14% for the SiO 2/Si morphologies. For the two morphologies in which the Cu 2p 3/2 or O 1s peak intensity was attenuated by an overlayer, the ratios of film thicknesses with elastic scattering switched on to those with elastic scattering switched off varied approximately linearly with the single-scattering albedo, a convenient measure of the strength of elastic scattering. This variation was similar to that of the ratio of the effective attenuation length to the inelastic mean free path for the photoelectrons in the overlayer film. For the two morphologies in which the Cu 2p 3/2 or O 1s photoelectrons originated from an overlayer film, the ratios of film thicknesses with elastic scattering switched on to those with elastic scattering switched off varied more weakly with the single-scattering albedo. This weaker variation was attributed to the weaker effects of elastic scattering for photoelectrons originating predominantly from near-surface atoms than for photoelectrons that travel through an overlayer film.</p
Inelastic background analysis of HAXPES spectra: towards enhanced bulk sensitivity in photoemission
Full text linkWe report on quantitative inelastic background analysis in hard X-ray photoelectron spectroscopy at high excitation energy (12-18 keV) using the Tougaard method implemented with careful optimisation of the inelastic scattering cross section. Such a method enables the determination of the in-depth elemental distribution over depths up to70 nm. We studied three parameters and investigate their influence on the results: the depth of the layer increases the uncertainty, the thickness and composition of the layer has an influence on statistics, and the excitation energy that must be chosen as a trade-off between high probing depth and low photoionization cross section. We show how this promising method can be used to follow diffusion of a 1-ML La layer after annealing a technologically relevant sample.</p
Effects of cation compositions on the electronic properties and optical dispersion of indium zinc tin oxide thin films by electron spectroscopy
Full text linkThe electronic properties and optical dispersion of indium zinc tin oxide (IZTO) films with different cation compositions were investigated by reflection electron energy loss spectroscopy (REELS). The REELS spectra of IZTO films revealed that the band gap varied with different Sn/Zn ratios and In content. The optical properties were examined with REELS data using Tougaard-Yubero model and the results were compared with the envelope of the transmission spectra obtained using a UV-spectrometer. The dispersion behavior of the refractive index from REELS results was studied in terms of the single-oscillator Wemple-DiDomenico model. The results showed that the different compositions of In/Zn/Sn caused a change in the dispersion parameters of IZTO thin films in contrast to the static values of refractive indices and dielectric constant which remained the same. Our work demonstrated that REELS is an efficient tool to study the optical properties of a material by obtaining the optical parameters.</p
- …
