Cross Sections for Electron?Carbon Monoxide Collisions in the Range 1?4 eV

Abstract

The scattering of electrons from CO molecules has been studied over the energy range from 1 to 4 eV by analysing drift velocity data for pure CO and CO-inert gas mixtures at 294 K. The validity of using the so-called 'two term approximation' for the velocity distribution function in the solution of the Boltzmann equation to analyse drift velocity data for the pure gas (and thus also for the gas mixtures) has been established. The momentum transfer cross section for CO has been determined in the energy range 1-4 eV, and the measurements of the vibrational cross sections by Ehrhardt et al. (1968) have been renormalized. By using a solution of the Boltzmann equation which avoids the two term approximation, these cross sections have been shown to be consistent with previous measurement.s of the transport parameter D 1.1 fl in pure CO.

Electron Transport Coefficients in Carbon Monoxide and Deuterium

“…Under certain conditions, Haddad and Milloy (1983) reported large background currents due to negative ions in their drift velocity experiments which prevented them from making measurements at pressures greater than 1 kPa and E/N less than 10 Td. Mass spectrometric analysis of the gas from the cylinder of CO (Matheson Research Grade) used by them revealed that low levels of impurity were present which apparently did not affect their values of Vdr (except perhaps at E/N = 10 Td-see Section 4) but were the major source of the background.…”

“…Drill with values calculated using the Haddad and Milloy (1983) cross sections shows that some modifications to their cross sections are required. This is to be expected given the discrepancies between the calculated and measured values of DTIIl shown in Fig.…”

“…For this application data of high accuracy are required in order to obtain the derived cross sections with adequate accuracy and uniqueness (Huxley and Crompton 1974;Morrison et al 1987). Hake and Phelps (1967) were the first to analyse electron transport data for CO to determine a set of elastic and inelastic cross sections compatible with the data for CO then available. The most interesting feature of their results was the demonstration of the importance of non-resonant vibrational excitation at energies less than 1 eV before the onset of the 2n shape resonance with its maximum at about 2 eV.…”

Higher lying resonances in low-energy electron scattering with carbon monoxide*

“…Different scattering models can be constructed by choosing different types of expansions for the target wave function (Φ N i ) and the corresponding L 2 configurations in equation (1). Generally three different models are used, namely, the static exchange (SE), SE plus polarization (SEP) and the close-coupling (CC) models.…”

“…This resonance has been wellcharacterised experimentally [1][2][3][4][5] and is the subject of a number of theoretical studies [3,[6][7][8][9]. This resonance provides the main mechanism for electron impact vibrational excitation [9,10] but lies too low in energy to lead to dissociative electron attachment (DEA) unless the CO target is also vibrationally excited [10].…”