Electron-impact ionization and dissociation of C2D+

Abstract

Absolute cross sections for electron-impact single ionization, dissociative excitation and dissociative ionization of the ethynyl radical ion (C2D+) have been measured for electron energies ranging from the corresponding reaction thresholds to 2.5 keV. The animated crossed electron-ion beam experiment is used and results have been obtained for the production of C2D2+, C2+, C+2, CD+, C+ and D+. The maximum of the cross section for single ionization is found to be (2.01 ± 0.02) × 10-17 cm2, at the incident electron energy of 105 eV. Absolute total cross sections for the various singly charged fragments production are observed to decrease by a factor of almost three, from the largest cross-section measured for C+, over C+2 and CD+ down to that of D+. The maxima of the cross sections are obtained to be (14.5 ± 0.5) × 10-17 cm2 for C+2, (12.1 ± 0.1) × 10-17 cm2 for CD+, (27.7 ± 0.2) × 10-17 cm2 for C+ and (11.1 ± 0.8) × 10-17 cm2 for D+. The smallest cross section is measured to be (1.50 ± 0.04) × 10-18 cm2 for the production of the doubly charged ion C2+. Individual contributions for dissociative excitation and dissociative ionization are determined for each singly-charged product. The cross sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. Kinetic energy release distributions of dissociation fragments are seen to extend from 0 to 6 eV for the heaviest fragment C+2, up to 11.0 eV for CD+, 14.2 eV for C+ and 11.2 eV for D+ products.