Surface Data

 
Surface Data 

The surface databases provide data for surface analysis by Auger-electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). In addition, the NIST Electron Elastic-Scattering Cross-Section Database (SRD 64) and the NIST Database of Cross Sections for Inner-Shell Ionization by Electron or Positron Impact (SRD 164) provide data for Monte Carlo simulations of electron transport in matter and for applications in atomic physics, plasma physics, radiation physics, and materials analysis by electron-probe microanalysis.

SRD 20 NIST X-ray Photoelectron Spectroscopy 4.1, PC, Online
SRD 64 NIST Electron Elastic-Scattering Cross-Section Database, PC, Online
SRD 71 NIST Electron Inelastic-Mean-Free-Path Database, PC
SRD 82 NIST Electron Effective-Attenuation-Length Database, PC
SRD 100 NIST Database for the Simulation of Electron Spectra for Surface Analysis (SESSA), PC, MAC, LIN
SRD 154 NIST Backscattering-Correction-Factor Database for Auger Electron Spectroscopy, PC
SRD 164 NIST Database of Cross Sections for Inner-Shell Ionization by Electron or Positron Impact

Highlights

The NIST X-ray Photoelectron Spectroscopy Database (SRD 20) contains over 33,000 data records that can be used for the identification of unknown lines, retrieval of data for selected elements (binding energy, Auger kinetic energy, chemical shift, and surface or interface core-level shift), retrieval of data for selected compounds (according to chemical name, selected groups of elements, or chemical classes), display of Wagner plots, and retrieval of data by scientific citation. For the newer data records, additional information is provided on the specimen material, the conditions of measurement, and the analysis of the data. Version 4.1 contains new reference photoelectron binding energies, reference Auger-electron kinetic energies, and reference Auger parameters for many elemental solids. These reference energies were derived from analyses of Handbook data [C. J. Powell, J. Electron Spectrosc. Relat. Phenom. 185, 1 (2012)] and are used in calculations of chemical shifts. 

The NIST Electron Elastic-Scattering Cross-Section Database (SRD 64) provides values of differential elastic-scattering cross sections, total elastic-scattering cross sections, and transport cross sections for elements with atomic numbers from 1 to 96 and for electron energies between 50 eV and 300 keV (in steps of 1 eV). Knowledge of elastic-scattering effects is important for the development of theoretical models for quantitative analysis by AES, XPS, electron microprobe analysis, and analytical electron microscopy. The database is designed to facilitate simulations of electron transport for these and similar applications in which electron energies from 50 eV to 300 keV are utilized. An analysis of available elastic-scattering cross-section data has been published by A. Jablonski, F. Salvat, and C. J. Powell, J. Phys. Chem. Ref. Data 33, 409 (2004).

The NIST Electron Inelastic-Mean-Free-Path Database (SRD 71) provides values of electron inelastic mean free paths (IMFPs) principally for use in surface analysis by AES and XPS. The database includes IMFPs calculated from experimental optical data and IMFPs measured by elastic-peak electron spectroscopy (EPES). If no calculated or measured IMFPs are available for a material of interest, values can be estimated from the predictive IMFP formulae of Tanuma et al. and of Gries. IMFPs are available for electron energies between 50 eV and 10,000 eV although most of the available data are for energies less than 2,000 eV. The cited reference also reviews measurements and calculations of IMFPs. A critical review of calculated and measured IMFPs has been published [C. J. Powell and A. Jablonski, J. Phys. Chem. Ref. Data 28,19 (1999)].

The NIST Electron Effective-Attenuation-Length Database (SRD 82) provides values of electron effective attenuation lengths (EALs) in materials at user-selected electron energies between 50 eV and 2,000 eV. The database was designed mainly to provide EALs (to account for effects of elastic-electron scattering) for measurements of the thicknesses of overlayer films and, to a much lesser extent, for measurements of the depths of thin marker layers. EALs are calculated using an algorithm based on electron transport theory for measurement conditions specified by the user. A critical review on the EAL has been published recently [A. Jablonski and C. J. Powell, J. Phys. Chem. Ref. Data 49, 033102 (2020)]. A practical guide for IMFPs, EALs, mean escape depths, and information depths has also been published recently [C. J.Powell, J. Vac. Sci. Technol. A 38, 023209 (2020); erratum J. Vac. Sci. Technol. A 38, 057001 (2020)].

Version 2.2 of the NIST Database for the Simulation of Electron Spectra for Surface Analysis (SESSA) (SRD 100) can be used to simulate AES and XPS spectra of nanostructures such as islands, lines, spheres, and layered spheres on surfaces. As for earlier versions, such simulations can also be performed for multilayer films. Users can specify the compositions and dimensions of each material in the sample structure as well as the measurement configuration. The database contains extensive physical data needed for quantitative interpretations of observed spectra. A more detailed description of SESSA was published in 2005 [W. Smekal, W. S. M. Werner, and C. J. Powell Surf. Interface Anal. 37, 1059 (2005)]. A more recent publication [W. S. M. Werner and C. J. Powell, J. Vac. Sci. Technol. A 39, 063205 (2021)] describes new functionalities of SESSA and gives examples of its use for quantitative XPS of nanostructures.

The NIST Backscattering-Correction-Factor Database for Auger Electron Spectroscopy (SRD154) provides values of backscattering correction factors (BCFs) of homogeneous materials for quantitative surface analyses by AES. These BCFs are obtained from Monte Carlo simulations based on two models of electron transport in the material, a simplified model and an advanced model [A. Jablonski and C. J. Powell, Surf. Science 604, 1928 (2010)]. One assumption for the former model is that the primary-electron beam is unchanged, in intensity, energy or direction, within the information depth for Auger-electron emission. This assumption becomes progressively less useful as the primary energy becomes closer to the core-level ionization energy for the relevant Auger transition or for increasing angles of incidence of the primary electrons.

The NIST Database of Cross Sections for Inner-Shell Ionization by Electron or Positron Impact (SRD 164) provides cross sections for ionization of the K shell and of the L and M subshells of neutral atoms of the elements, from hydrogen to einsteinium, by electrons or positrons, for projectile energies from the ionization threshold to 1 GeV. These cross sections were calculated from a combination of the relativistic distorted-wave and the plane-wave Born approximations. Extensive comparisons have been made of the calculated cross sections for inner-shell ionization by electron impact with available experimental data that satisfied mutual-consistency checks. These comparisons showed that the overall root-mean-square deviation between measured and calculated cross sections was 10.9 % [X. Llovet, C. J. Powell, A. Jablonski, and F. Salvat, J. Phys. Chem. Ref. Data 43, 013102 (2014)].  

The codes in the list below have the following meanings: