Evaluation of the inelastic mean free path (IMFP) of electrons in polyaniline and polyacetylene samples obtained from elastic peak electron spectroscopy (EPES)

Abstract

The inelastic mean free path (IMFP) of electrons was determined experimentally for selected polyaniline and polyacetylene samples with Ag and Ni references using elastic peak electron spectroscopy (EPES). The surface composition was determined by XPS and density by helium pycnometry. The high resolution hemispherical ESA-31 and ADES-400 spectrometers were used for measurements in the energy range E = 0.5–3.0 keV and E =0.4 − 1.6 keV, respectively. The integrated elastic peak intensity ratios for sample and reference were calculated using the Monte Carlo (MC) algorithm based on the electron elastic scattering cross-sections database NIST SRD64 version 3.1 and applying TPP-2M IMFPs for polymers. Surface excitation parameters (SEP) and material parameters (ach) for polymers were determined, using the model of Chen, from comparison of measured and MC calculated elastic peak intensity ratios. These corrections proved to be efficient in decreasing the percentage deviations between the obtained IMFPs and the TPP-2M formula IMFPs. The elastic peak of hydrogen was observed in the EPES spectra of polymers. The experimental contribution of the hydrogen to the total elastic peak was 0.58%, while this value obtained from the MC simulations was 1.98%.

Inelastic scattering of electron and light ion beams in organic polymers

“…2(d) were reported in the more recent publication. 58 The slope of these data cannot be reproduced by any model. Nevertheless, the same group reports very different experimental values in its previous publications.…”

Influence of Recoil Effect and Surface Excitations on the Inelastic Mean Free Paths of Electrons in Polymers

“…Surface morphology, line scans and values of average surface roughness (between 5.59-19.93 nm) reported elsewhere [18,28] show negligible differences among the three polythiophenes. The PDOBT sample, however, seems to be different from the others having the largest surface roughness.…”

“…Values of a ch for selected elements have been proposed [23]. Otherwise, the material parameters by Werner et al [22], a H , and by Chen [23], a ch , for any multicomponent material can be estimated from the EPES [18,19,28] and reflection electron energy loss spectroscopy (REELS) methods [19]. For correcting the IMFPs due to surface excitation the measured intensity ratios are multiplied by the reciprocal of the surface excitation correction factor, f s :…”

“…The surface excitation parameters for polythiophenes investigated in the present work are calculated from Eq. (5) using Chen's material parameters, a ch , evaluated by the EPES method [28], i.e. : POT -1.25, PDOBT -1.25, PDDoBT -2.5.…”

Stopping powers and inelastic mean free path from quantitative analysis of experimental REELS spectra for electrons in Ti, Fe, Ni, and Pd

“…In this study, we have used the ELF from the quantitative analysis of experimental REELS in determining SPs and IMFPs of Fe, Ni, Pd, and Ti for electron energies from 150 eV to 10 keV. The ELF in this study was taken from previous publications for Ni from Tahir et al and Fe, Pd, and Ti from Tahir et al The SPs were compared with several method of calculations; Bethe in Tahir et al and Tanuma et al, Nguyen‐Truong, Joy and Luo, and Jablonski et al and the IMFP compared with Tanuma Powell Penn (TPP2M) methods, which can be freely downloaded from http://www.quases.com/products/quases-imfp-tpp2m/, from the previous studies, and also NIST from http://www.nist.gov/index.html . The purpose of this work is to provide alternative basic data from the experimental determination of SP and IMFP for the study electrons transport through Ti, Fe, Ni, and Pd.…”