State selected ion–molecule reactions by the TESICO technique. XIII. Vibrational state dependence of the cross sections in the reaction C2D+2(ν2)+H2

Abstract

Vibrational-state selected reaction cross sections have been measured for three product channels of the reaction C2D+2(ν2)+H2, by use of the threshold electron–secondary ion coincidence (TESICO) technique. The ν2 vibrational states of the C2D+2 ion were selected up to v=2 and the collision energies were changed from 0.1 to 2.0 eV. At low collision energies up to 0.2 eV, considerable enhancement of the cross sections for the channel producing C2D2H+ was observed when the vibrational quantum number was increased successively. As the collision energy was increased, the extent of this enhancement diminished gradually and the cross section became almost independent of v at 2.0 eV. The cross section for the H/D exchange channel, on the other hand, was found to decrease with increasing vibrational quantum number at low collision energies. The latter cross section also became independent of v at high collision energies. These results have been explained in terms of the formation of an intermediate complex and the statistical decomposition of this complex to products.