Reactions of Ar+with halocarbons and of I+with CF3I

摘要

The gas phase reactions of Ar+with the halocarbons CF3Cl, CF3Br, CF3I, CF4, C2F6, and C2F4have been studied using a variable temperaturehyphen;selected ion flow tube (VThyphen;SIFT) instrument operated at 298 and 500 K. Rate constants and product branching percentages were measured at both temperatures. Ar+reacts at the collisional rate with all of the above neutrals at both 298 and 500 K. The reactions with CF3X yield CF+3and CF2X+for all X (the reaction with CF4produces only CF+3). For X=I, there is an additional channel leading to the ionic product I+. The reaction of Ar+with C2F6produces both CF+3and C2F+5. The reaction of Ar+with C2F4forms a rich product spectrum consisting of the ions CF+, CF+2, CF+3, C2F+3, and C2F+4. The reaction product distributions are compared with results from ionization experiments such as photoionndash;photoelectron coincidence (PIPECO) and electron impact mass spectrometry, and in some cases excellent agreement is found. The reaction of I+with CF3I, which is a secondary reaction in the Ar+/CF3I system, was investigated at 298 K in separate experiments. This reaction is rapid and forms four product ions: CF+3, CF2I+, CF3I+, and I+2. The results are compared with previously published information.