Two new sets of optical data, i.e., values for the real (ε1) and imaginary (ε2) parts of the complex dielectric constant as well as the energy loss function (ELF) (Im{−1∕ε}), are presented for 16 elemental metals (Ti, V, Fe, Co, Ni, Cu, Zn, Mo, Pd, Ag, Ta, W, Pt, Au, Pb, and Bi) and 1 semimetal (Te) and are compared to available data in the literature. One data set is obtained from density functional theory (DFT) calculations and gives ε from the infrared to the soft x-ray range of wavelengths. The other set of optical constants, derived from experimental reflection electron energy-loss spectroscopy (REELS) spectra, provides reliable optical data from the near-ultraviolet to the soft x-ray regime. The two data sets exhibit very good mutual consistency and also, overall, compare well with optical data found in the literature, most of which were determined several decades ago. However, exceptions to this rule are also found in some instances, some of them systematic, where the DFT and REELS mutually agree significantly better than with literature data. The accuracy of the experimental data is estimated to be better than 10% for the ELF and ε2 as well as for ε1 for energies above 10eV. For energies below 10eV, the uncertainty in ε1 in the experimental data may exceed 100%, which is a consequence of the fact that energy-loss measurements mainly sample the absorptive part of the dielectric constant. Electron inelastic-scattering data, i.e., the differential inverse inelastic mean free path (IMFP) as well the differential and total surface excitation probabilities are derived from the experimental data. Furthermore, the total electron IMFP is calculated from the determined optical constants by employing linear response theory for energies between 200 and 3000eV. In the latter case, the consistency between the DFT and the REELS data is excellent (better than 5% for all considered elements over the entire energy range considered) and a very good agreement with earlier results is also obtained, except for a few cases for which the earlier optical data deviate significantly from those obtained here.

The influence of electron transport on the signal generation process in electron beam techniques is reviewed. A survey of the fundamental physical quantities for the electron-solid interaction is presented and sources for these quantities in the literature as well as semi-empirical formulae are given. The theoretical approaches used to describe multiple scattering in solids are outlined. These include the partial intensity approach and the continuous slowing down approximation to describe multiple energy losses and the transport approximation to tackle multiple deflections. A detailed description of the Monte Carlo technique is presented because this constitutes an effective means to study transport processes. The different theoretical approaches are illustrated in a survey of applications. These include: quantitative description of the surface sensitivity in Auger and photoelectron spectroscopy; line shape analysis of electron spectra; extracting information on the compositional depth profile from the combined energy/angular distribution in an electron spectrum; quasi-elastic electron reflection; inelastic electron backscattering; depth distribution of production of x-rays caused by electron bombardment; and the surface sensitivity in total electron yield electron spectroscopy. These applications demonstrate that the outlined approaches have a broad field of application, not only for electrons with energies ranging from thermal to the relativistic energy range, but also for other microbeam analysis techniques.

A description of a new NIST database for quantitative Auger-electron and X-ray photoelectron spectroscopy (AES/XPS) is given: Simulation of Electron Spectra for Surface Analysis (SESSA). This database contains extensive sets of data for the physical quantities relevant to AES and XPS. The internal databases are linked to a user interface via a small expert system that allows a user to automatically retrieve data needed for a specific practical application. SESSA can simulate AES and XPS spectra for a multilayered thin-film sample for measurement conditions specified by the user. Experimental information needed by SESSA is entered via an interface that matches the settings of AES/XPS instrumentation. The structure of SESSA is described together with information on special features, unique capabilities, and sources of the physical data. Examples of practical applications of SESSA for angle-resolved XPS on Al and Si samples, determination of the depth distribution function in XPS, and the use of empirical peak shapes for spectrum simulation are given. These and other applications are contained in SESSA in the form of tutorial files with command-language statements that can be loaded into SESSA and modified as necessary for similar simulations.

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