EXPERIMENTAL-DETERMINATION OF THE RADIATIVE LIFETIMES OF CF-1-SIGMA(+),V) IONS((X)

The internal energy content of CF+(X-1 Sigma(+),v) ions and its time e volution have been probed using the monitor ion technique in a triple FTICR spectrometer. Vibrationally excited CF+ ions were produced by el ectron impact on CF3H. Charge transfer reactions on NO, C2H5I, CH3I an d CS2 were used in this study. The experimental overall lifetimes obta ined for vibrational levels v greater than or equal to 1 (23 +/- 5) ms and v greater than or equal to 2 (13.5 +/- 3) ms are much larger (70% and 100%, respectively) than published lifetimes obtained by ab initi o calculation for v = 1 and v = 2. This can be accounted for by a radi ative cascade from higher vibrational levels (v greater than or equal to 3). Computer simulations using the theoretical lifetimes and a Bolt zmann distribution for the initial vibrational populations have been p erformed. An initial distribution corresponding to kT = 1.0 eV gives s imulated lifetimes close to our experimental results. (C) 1997 Elsevie r Science B.V.