II. Electron-impact dissociative excitation of C2H 2 + and C2D 2 +

Abstract

Absolute cross-sections for electron-impact dissociative excitation of C2H (2) (+) and C2D (2) (+) to C2D+, CH+, C+, C (2) (+) , H+ and CH (2) (+) singly-charged fragments have been estimated. The animated crossed-beams method is applied in the energy range from the corresponding reaction threshold up to 2.5 keV. Individual contributions for dissociative excitation are determined from the analysis of the total absolute cross-sections measured for each detected product. The dissociative excitation cross-sections are seen to decrease for more than an order of magnitude, from C2D+ (12.6 +/- 0.3) x 10(-17) cm(2) over CH+ (6.37 +/- 0.12) x 10(-17) cm(2), C+ (4.09 +/- 0.13) x 10(-17) cm(2), C (2) (+) (3.5 +/- 0.2) x 10(-17) cm(2) and H+ (1.57 +/- 0.11) x 10(-17) cm(2) to CH (2) (+) (3.6 +/- 0.5) x 10(-18) cm(2). Cross-section values and threshold energies are compared with the data which are available from the literature.