Differential probability for surface and volume electronic excitations in Fe, Pd and Pt

TL;DR

This paper introduces a novel method to accurately distinguish surface and volume electronic excitations in Fe, Pd, and Pt using REELS spectra, improving upon previous techniques by providing unique scattering loss distributions.

Contribution

A new deconvolution procedure is proposed that separates surface and volume scattering contributions from REELS spectra, addressing limitations of existing methods.

Findings

The method yields a unique reconstruction of scattering loss distributions.

It demonstrates that previous methods produce mixed scattering distributions.

The approach is validated with both model spectra and experimental data.

Abstract

The normalized differential mean free path for volume scattering and the differential surface excitation probability for medium energy electrons travelling in Fe, Pd and Pt are extracted from Reflection Electron Energy Loss Spectra (REELS). This was achieved by means of a recently introduced procedure in which two REELS spectra taken under different experimental conditions are simultaneously deconvoluted. In this way, it is possible to obtain the unique reconstruction for the surface and volume single scattering loss distribution. The employed method is compared with a procedure that is frequently used for this purpose [Tougaard and Chorkendorff, Phys. Rev. B 35(1987)6570]. It is shown, both theoretically and through analysis of model spectra as well as experimental data that this method does not result in a {\em single} scattering loss distribution. Rather, it gives a mixture of surface, bulk and mixed scattering of any order.