A comparison of ERBS spectra of compounds with Monte Carlo simulations

Abstract

Electron Rutherford backscattering measures the near-surface composition of samples quantitatively. For interpretation, one usually relies on the single-scattering approximation. Here, we present results for four compounds, containing oxygen and other species, varying from very light to very heavy. Two Monte Carlo codes are described that model these measurements. From these simulations, it is clear that for all samples, multiple scattering occurs frequently, but also that the single scattering interpretation deduces the right composition, except for O atoms in a very heavy matrix, where interpretation is more difficult. The intrinsic width of the peaks, a consequence of Doppler broadening due to the velocity of the (vibrating) atoms, turns out to be more sensitive to multiple scattering effects.

Electron-induced hydrogen desorption from selected polymers (polyacetylene, polyethylene, polystyrene, and polymethyl-methacrylate)

“…determination of the electron inelastic mean free path Varga et al [7] energy shift and broadening (graphite, Si, Ni, and Au) Yubero et al [8] hydrogen content in diamond-like carbon films Alvarez and Yubero [9] quantification of hydrogen content at surfaces (polyethylene) Vos et al [10] experiments and MC (Li 2 CO 3 , CaCO 3 , TiO 2 , and HfO 2 ) Vos [11] electron scattering experiments (thin films of formvar) Chatzidimitriou et al [12] comparing experiments involving ECS and NCS Ultimately, as outlined by Filippi and Calliari [4], the primary factors contributing to uncertainty in hydrogen quantification through EPES involve both data management (e.g., background subtraction) and the incorrect assumption that the surface composition of reference materials matches the bulk composition. Notably, electron beam-induced damage is likely the most crucial concern in this context.…”

“…An accurate description of the shape of the experimental elastic peak can be achieved through Monte Carlo simulations of EPES, as demonstrated, for example, in references [6,10,13,14]. This approach proves highly effective in capturing the outcomes of many small-angle scattering events and allows us to easily investigate the effects of electron-beam-induced hydrogen desorption.…”

“…Vos et al [10] presented spectra of Li 2 CO 3 , CaCO 3 , TiO 2 , and HfO 2 and demonstrated that it is possible to obtain the composition of compounds with reasonably high accuracy (from 1%-2% error for CaCO 3 and TiO 2 to 5%-20% for Li in Li 2 CO 3 or O in HfO 2 ).…”