Mobility of CF3+ in CF4, CHF2+ in CHF3, and C+ in Ar

A drift tube-double mass spectrometer technique has been used to study the transport of CF3+ in CF4 and of CHF2+ in CHF3. The reduced mobilities of these two ions were measured over the density-normalized electric field strength E/N, between 30 and 750 Td (1 Td=10(-17) V cm(2)). It was found that substantial amounts of C+ were produced thorugh the reaction of CF3+ with Ar. Thus, the mobility of C+ could be measured over the E/N range from 30 to 260 Td. Further measurements of the abundance of secondary ions formed by the reactions of CF3+ and CHF2+ with Ar revealed that for E/N>250 Td and E/N>120 Td, respectively, Ar+ predominates as a secondary species over F+, CF+, CF2+, and ArH+. The injection of Ar+ into CF4 was also found to be a very efficient dissociative charge transfer process, leading predominantly to CF3+ formation, with conversion efficiencies of practically 100% for E/N>100 Td. The above finding is consistent with a previous beam study. (C) 2002 American Institute of Physics.