The NIST surface analysis data center

Abstract

NIST has recently established a Surface Analysis Data Center to give greater visibility to its databases developed for applications in surface analysis. Two databases are currently available for this purpose, and a third will be released soon. These three databases are described briefly here. Version 2.0 of the popular X-ray Photoelectron Spectroscopy Database (SRD 20) was released in 1997. This database has long been a valuable resource of binding-energy and related data for the surface analysis of a wide range of materials by x-ray photoelectron spectroscopy (XPS). Version 2.0 contains about 16,000 line positions, chemical shifts, and splittings. Pull-down menus are now available to initiate searches for the identification of unknown lines, to retrieve data on core-level binding energies, to retrieve data on chemical shifts, to initiate searches for compounds containing selected elements or for specified material classes, to perform searches based on compound names and other fields, and to display Wagner plots.Version 1 of the Elastic-Electron-Scattering Cross-Section Database (SRD 64) was released in 1996. This database provides differential and total elastic-electron-scattering cross sections for simulations of signal-electron transport in XPS and Auger-electron spectroscopy (AES). Such simulations are important in the development of improved methods for correcting for elastic-electron-scattering effects in quantitative surface analyses by AES and XPS and for separating chemical information from effects due to the complex morphologies of semiconductor structures. Cross sections are given for all elements and for electron energies between 50 and 9,999 eV. The Electron Inelastic-Mean-Free-Path Database (SRD 71) will be released in 1998. This database contains calculated and measured inelastic mean free paths (IMFPs) that are needed for quantitative surface analyses by AES and XPS. The IMFPs are available for elements, inorganic compounds, and organic compounds as a function of electron energy. IMFPs can also be obtained conveniently from various predictive formulae. Once a data source is selected, the user can choose to display the information graphically (that is, a plot of IMFP versus electron energy) or as values for one or more specified electron energies.