III. Electron-impact dissociative ionization of C2H +2 and C2D +2

Abstract

Absolute cross-sections for electron-impact dissociative ionization of C2 H +2 and C2 D +2 to CH+, C+, C +2 , H+, CH +2 and C2D+ fragments are determined for electron energies ranging from the corresponding threshold to 2.5 keV. Results obtained in a crossed beams experiment are analyzed to estimate the contribution of dissociative ionization to each fragment formation. The dissociative ionization cross sections are seen to decrease for more than an order of magnitude, from CH+ (5.37±0.10) × 10-17 cm2 over C+ (4.19± 0.16) × 10-17 cm2, C2D+ (3.94±0.38) × 10-17 cm2, C +2 (3.82±0.15) × 10-17 cm2 and H+ (3.37±0.21) × 10-17 cm2 to CH +2 (2.66±0.14) × 10-18 cm2. Kinetic energy release distributions of fragment ions are also determined from the analysis of the product velocity distribution. Cross section values, threshold energies and kinetic energies are compared with the data available from the literature. Conforming to the scheme used in the study of the dissociative excitation of C2H +2 (C2D+2), the cross-sections are presented in a format suitable for their implementation in plasma simulation codes.