Communications: Photoinitiated bond dissociation of bromoiodomethane in solution: Comparison of one-photon and two-photon excitations and the formation of iso- CH2 Br-I and iso- CH2 I-Br

Abstract

Broadband UV-visible femtosecond transient absorption spectroscopy was used to monitor the excited state photochemistry of CH2 BrI following one-photon excitation at 266 or 271 nm and two-photon excitation at 395 or 405 nm in 2-butanol. The results for one-photon excitation agree with earlier studies in acetonitrile, showing clear formation of iso- CH2 Br-I following cleavage of the C-I bond. In contrast, two-photon excitation at 395 nm results in the appearance of a blueshifted photoproduct absorption band assigned to formation of iso- CH2 I-Br following cleavage of the C-Br bond. The results are discussed in the context of prior experimental and theoretical work and the prospects for optical control of bond cleavage. © 2010 American Institute of Physics.