Isotope effects in electron-impact dissociation of D2H+

P Defrance (1) , J J Jureta (1, 2) , J Lecointre (1) , X Urbain (1)

1 IMCN - Institut de la matière condensée et des nanosciences / Institute of Condensed Matter and Nanosciences
2 Institute of Physics

Absolute cross sections have been measured using the crossed electron-ion beams method for electron-impact dissociation of the D 2 H + molecular ion yielding H +, D +, HD + and + 2 D fragments. The collision energy ranges from a few eV up to 2.5 keV. Around the maximum, cross sections are found to be of similar amplitude: (3.25±0.08)×10 -17 cm 2 for H +, (3.56±0.15)×10 -17 cm 2 for HD + and (3.33±0.11)×10 -17 cm 2 for + 2 D ; except for D + for which the maximum cross section is (4.62±0.09)×10 -17 cm 2. Individual contributions for dissociative excitation and for dissociative ionization are determined for each product. Close analysis of present data brings into evidence isotope effects in the fragmentation pattern of the D 2 H + target. Ejection of the lightest isotope is generally favored: for resonant dissociative excitation (H + over D +), for dissociative excitation (molecular ions + 2 D and HD +, associated with ejection of H and D, respectively) and for dissociative ionization, but not for H + and D + produced via dissociative excitation. Present dissociative excitation cross sections for D 2 H + are found to be significantly lower than those measured for + 3 D, although those of DI agree well together.

Mots clés: : 34-80; 52-20 Key words: deuterium; hydrogen; isotope; molecular ion; electron-ion collision; ionization; excitation; dissociation; cross section.; cross section

P Defrance, J J Jureta, J Lecointre, X Urbain. Isotope effects in electron-impact dissociation of D2H+. Journal of Physics B: Atomic, Molecular and Optical Physics, 2011, 44 (7), pp.75202. ⟨10.1088/0953-4075/44/7/075202⟩. ⟨hal-00608727⟩