Electron interactions with tetramethylsilane from the ionization threshold up to 5000 eV

Abstract

The electron impact cross sections are reported for tetramethylsilane from the ionization threshold up to 5000 eV. The partial ionization cross sections (PICS) of the fragments created by ionization are obtained using a modified form of the binary-encounter Bethe (BEB) model. These fragments have a mass to charge ratio (m/z) ranging from 15 to 88. In the modified-BEB approach, the binding energy of each molecular fragment is increased in such a way that the last occupied orbital reflects the appearance potential of a particular fragment. The total ionization cross sections obtained after summing the PICS are in very good agreement with the experimental results. Additionally, the cross sections such as differential, integral and momentum transfer are also reported. These are computed within the local potential approximation and invoking single centre expansion formalism. The total cross sections are obtained by incoherently summing the elastic and inelastic cross sections. The present scattering results are in excellent agreement with the experimental measurements. The modified-BEB model will be an immense help in understanding the effect of ionization on fragments.

Electron impact cross-sections of tetraethyl silicate

“…However, there is no data available to compare the present results. It has been shown in earlier studies [63,120] that this approach can yield reliable results. This gives us the encouragement to put forward our results for Q t .…”

“…j R j (E) = 1. The experimental BR can be calculated either from the relative cation abundance data determined from electron ionization mass spectrometry (MS) or from the experimental cross section data [63,69,70].…”

“…Therefore, simple and reliable methods are needed to obtain the electron impact cross sections not only for TEOS but for any complex molecular species in high energy regions. A straightforward approach at these energies is to compute cross sections for the elastic and inelastic processes separately and then sum them to obtain the total cross sections [63].…”

“…The semi-empirical BEB approach of Kim and Rudd [67] has yielded total ionization cross sections (TICS) effortlessly for many molecules [68]. A recently proposed variant of the BEB model named the modified BEB model (m-BEB) has yielded acceptable partial ionization cross sections (PICS) [63,69,70]. Both these models offer several advantages as these are free from fitting parameters, differential oscillator strengths and requires input quantities, which can be obtained from the standard quantum chemistry computer program packages like GAUSSIAN [71] and GAMESS [72].…”

A binary-encounter-Bethe approach to compute electron-impact partial ionization cross sections of plasma relevant molecules such as hexamethyldisiloxane and silane

“…Although semi-empirical models such as binary-encounter-Bethe (BEB), Deutch-Märk (DM) and Jain-Khare (JK) are used to compute TICS [29][30][31], relatively fewer computations have been made for PICS using semi-empirical models. Very recently, a modified form of the BEB model for electrons was invoked to determine PICS of the fragments created due to dissociation-ionization [32][33][34]. This approach is much simpler than the modified JK model [35,36] as it does not require any information about collision parameters and differential oscillator strengths.…”