excitation is believed to involve the = 0 -*• 1 transition and thus is a measure of the fundamental vibration for the ion.3 Although ion-matrix electronic interactions are on the order of 1 eV,22 differences in interactions between ground and excited vibrational states are probably small, and vibrational spectra of matrix-isolated molecular ions are believed to be representative of the gaseous ion. The fact that argon-krypton matrix differences are small (5-7 cm"1) for such ions as CF3+ and CHBr2+, which are only slightly larger than the 4-cm'1 3argon-krypton matrix difference for CF3 and CHBr2 radicals,1,9,23,24 suggests that the gas-to-argon matrix shift for the vibrational fundamental of the ion is relatively small (~10 cm"1). This in turn suggests that even the low-intensity IRMPDS may involve higher vibrational manifold excitations and peak at slightly lower energy than the fundamental owing to normal cubic anharmonicity.Perhaps the most important information from the present study is that C-F vibrational modes in relatively large radical cations absorb at slightly higher frequencies than the corresponding modes of the neutral molecule. The effect on perfluoropropene is relatively small, ca. 29 and 17 cm"1 for the two modes. A much larger increase (21)

The deactivation processes of excited acridine, deuterated acridine, and 9-substituted acridines (9-methyl, 9-propyl, 9-chloro, and %amino) have been investigated in alkaline and acidic water. The photoreaction does not occur with the irradiation of 365-nm light. In acidic water the fluorescence lifetime T depends only slightly on the temperature and the lowest triplet yield +sT is negligibly low for all of the acridines. In alkaline water T decreases and +ST increases with increasing temperature; the intersystem crossing occurs through both temperaturedependent and temperature-independent processes. For all of the acridines except for 9-aminoacridine, the temperature-dependent process was attributed to the S1(a,a*) + (+Ai?) Sz(n,a*) -T3(a,a*) transition and the temperature-independent process mostly to the Sl(a,a*) -T2(n,a*) transition. The fact that the frequency factor of the temperature-dependent process increases with decreasing the energy gap between S2(n,a*) and S3(a,a*) was interpreted by the vibronic interaction between these states. In the case of 9-aminoacridine, the temperature dependence of r was tentatively attributed to the Sl(a,a*) -(+a) T2(n,a*) transition, because the energy level of T2(n,a*) was considered to be higher than that of Sl(a,a*) in contrast to the other acridines.

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