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

Electron attachment to SOF 2 , SOCl 2 , SO 2 F 2 , SO 2 FCl , and SO 2 Cl 2 was studied with two flowing-afterglow Langmuir-probe apparatuses over the temperature range 300-900 K. Attachment rate coefficients at 300 K are k a = 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.