Electron attachment to sulfur oxyhalides: SOF_2, SOCl _2, SO_2 F_2, SO_2 Cl_2, and SO_2 FCl attachment rate coefficients, 300-900 K

摘要

Electron attachment to SOF_2, SOCl_2, SO_2 F_2, SO_2 FCl, and SO_2Cl_2 was studied with two flowing-afterglow Langmuir-probe apparatuses over the temperature range 300-900 K. Attachment rate coefficients at 300 K are ka =2.6±0.8× 10-10 (SOF_2), 1.8±0.5× 10-8 (SOCl_2), 4.8±0.7× 10-10 (SO_2 F_2), 2.4±0. 7× 10-9 (SO_2 Cl_2), and 2.0±0.6× 10-7 cm_3 s-1 (SO_2 FCl). Arrhenius plots of the data imply activation energies of 56±22 meV (SOF_2), 92±40 (SO _2 F_2), 44±22 meV (SOCl_2), and 29±15 meV (SO_2 Cl_2). The rate coefficients for SO_2 FCl decrease slightly with temperature, commensurate with the decrease in the capture rate coefficient. Electron attachment to SOF_2 and SO_2 F_2 is nondissociative, while reaction with SOCl_2, SO_2 FCl, and SO_2 Cl_2 is dissociative. Dissociative attachment is dominated by channels arising from S-Cl bond cleavage but also includes a minor channel forming a dihalide product ion. Branching fraction data are reported for the dissociative attachment channels.