Deactivation of I(2P1/2) by CH3Cl, CH2Cl2, CHCl3, CCl3F, and CCl4

Abstract

Collisional deactivation of by the title compounds was investigated through 2

Absence of a Signature of Aqueous I(2P1/2) after 200-nm Photodetachment of I-(aq)

“…To date, no experimental lifetime has been reported for I* in a room-temperature liquid. In rare-gas matrixes, the I* lifetime is ∼5 ms, whereas a lower bound on the free I* lifetime in CCl 4 is ∼1 μs. , The relaxation rate can be strongly enhanced through quasiresonant electronic-to-vibrational energy transfer involving quadrupole−dipole coupling. − The highest rates occur when the energy gap between the I* → I transition and the acceptor mode is small, such as when water is the acceptor (with two quanta accepted into the OH stretching mode). Use of a binary collision model and that gas-phase rate for I* deactivation with H 2 O leads to an estimate of ∼160 collisions required to deactivate I*. , This still corresponds to ∼16 ps in room-temperature water, considerably slower than necessary to account for our experimental results.…”

“…46,47 The relaxation rate can be strongly enhanced through quasiresonant electronic-tovibrational energy transfer involving quadrupole-dipole coupling. [48][49][50][51] The highest rates occur when the energy gap between the I* f I transition and the acceptor mode is small, such as when water is the acceptor (with two quanta accepted into the OH stretching mode). Use of a binary collision model and that gas-phase rate for I* deactivation with H 2 O leads to an estimate of ∼160 collisions required to deactivate I*.…”