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NIST Standard Reference Database 82

NIST Electron Effective-Attenuation-Length Database

Version 1.1

This database provides values of electron effective attenuation lengths (EALs) in solid elements and compounds at 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 applications in surface analysis by Auger-electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS).

For these applications, EALs are needed mainly for measurements of the thicknesses of overlayer films and to a much lesser extent for measurements of the depths of thin marker layers. The EAL database incorporates needed transport mean free paths (TMFPs) and inelastic mean free paths from two other NIST database (SRD 64 and SRD 71). EALs are then calculated using an algorithm based on electron transport theory for measurement conditions specified by the user. Version 1.1 of SRD 82 uses TMFPs from Version 3.1 of SRD 64 whereas Version 1.0 of SRD 82 used TMFPs from Version 2.0 of SRD 64. The new TMFPs are believed more reliable than those used earlier.

The database supplies "local" EALs (derived from the slope of the emission depth distribution function (DDF) at a specified depth) and "practical" EALs suitable for measurements of overlayer-film thicknesses or depths of thin marker layers. For the latter applications, the database provides a table of practical EALs for a user-specified range of thicknesses or depths. These EALs are plotted as a function of thickness or depth, and an average value shown for a user-selected thickness or depth. An average practical EAL (for thickness measurements) can then be utilized as the "lambda parameter" to obtain overlayer-film thicknesses from simple equations in which the effects of elastic-electron scattering are neglected. A single average practical EAL can generally be employed for electron emission angles up to about 60o. Files with computed EALs can be created and used to prepare plots in which EALs for different conditions or for different materials can be compared. The EAL files and the plots can be printed and stored for use in other applications.

The database also supplies values of other parameters for an infinitely thick material: the electron mean escape depth, the correction parameters Qx and beta-eff for determination of surface composition by XPS, and the correction parameter QA for determination of surface composition by AES. In addition, a user can obtain the DDF for a specified material and measurement configuration, and the ratio of this DDF to the DDF found with elastic-electron scattering neglected.

System Requirements: Personal computer with Windows 2000, Windows ME, or Windows XP operating system, CD-ROM drive, and hard disc space of at least 7.3 MB.

Price: No Charge

Please click here to view the PDF version of Users' Guide.

 NIST Standard Reference Database 82

For more information please contact:

The scientific contact for the database is:

Key words: Auger electron spectroscopy,electron effective attenuation length,depth distribution function, surface analysis, x-ray photoelectron spectroscopy.