Electron impact excitation of the argon 3p⁵4s configuration: differential cross-sections and cross-section ratios

Abstract

New electron-impact differential cross-section (DCS) and DCS ratio measurements for the excitation of the four levels making up the 3p 5 4s configuration of argon are reported at incident electron energies of 14, 15, 17.5, 20, 30, 50 and 100 eV. These cross-sections were obtained using a conventional high resolution electron spectrometer. Elastic electron scattering from argon was used as a calibration standard. Electron-helium DCSs were used to determine the instrumental transmission of the spectrometer. Further checks of the relative shape of these DCS measurements were made using the method of gas mixtures (Ne mixed with Ar). We also present results from new calculations of these DCSs using the R-matrix method, the unitarized first-order manybody theory, the semi-relativistic distorted-wave Born approximation, and the relativistic distorted-wave method. Comparison with available experimental DCSs and DCS ratios is also presented.

Plasma-Chemical Kinetics of Film Deposition in Argon-Methane and Argon-Acetylene Mixtures Under Atmospheric Pressure Conditions

“…Therefore, the change in electron density and EVDF up on changing the precursor also changes the rate of electron impact excitation processes. The rate constants for electron impact acetylene and methane dissociation, argon ionization and argon metastables formation are determined (figure 14) using the equation (15), from the known values of cross-section for the corresponding process (Ballou et al, 1973;Belic et al, 2010;Garcıa & Manero, 1998;Khakoo et al, 2004) and the determined EVDF. Electron impact dissociation rate constant of precursor molecule is higher than the electron impact ionization rate constant of argon atom (figure 14).…”

Measuring the electron temperature by optical emission spectroscopy in two temperature plasmas at atmospheric pressure: A critical approach

“…This set is based mainly in experimental measurements and has been validated by the comparison with the argon swarm data, and especially with the measurements of excitation coefficients of Tachibana. 19 In order to get a good agreement, the measurements of Khakoo et al 20 for the argon metastable levels have been multiplied by a factor 0.5. For the upper excited levels for which there are no experimental data available, the Drawin formula for optically allowed transitions…”

Near-threshold electron-impact excitation of argon studied with the time-of-flight technique

“…Recently, Khakoo et al [3] extended the range of measurements on the electron-argon system much closer to the lowest excitation threshold by presenting measurements reaching down to an impact energy of 14 eV. Furthermore, they resolved the DCSs for the individual transitions to the four levels comprising the 3p 5 4s configuration of argon.…”

“…In an attempt to resolve discrepancies in the near-threshold region, we also performed measurements at the impact energies of 17.5 eV, 15.0 eV, and 14.0 eV considered by Khakoo et al [3] and then probed even closer to threshold than previous work by performing a measurement at 12.5 eV, i.e., only about 1 eV from the excitation threshold for the 3p 5 4s [3/2] state. In contrast to the measurements of Khakoo et al [3], we employ a time-of-flight spectrometer, which is particularly well suited to measuring energy-loss spectra in the near-threshold region due to its uni-0 2 form transmission.…”

“…In contrast to the measurements of Khakoo et al [3], we employ a time-of-flight spectrometer, which is particularly well suited to measuring energy-loss spectra in the near-threshold region due to its uni-0 2 form transmission. We do not, however, resolve the four levels comprising the 3p 5 4s manifold of argon as they did and, therefore, compare our results to their summed DCSs.…”