Ultraviolet photodissociation dynamics of methyl iodide at 333 nm.

The ultraviolet (UV) photodissociation dynamics of methyl iodide at 333.45 nm has been studied using resonantly enhanced multiphoton ionization in conjunction with a time-of-flight mass spectrometer (REMPI-TOFMS). At this wavelength methyl iodide photolysis involves a transition with significant parallel and perpendicular character. Both ground (I) and spin–orbit (I*) excited iodine result from a parallel transition to the 3Q0 state. In contrast, the perpendicular transition, which most likely involves initial excitation to the 3Q1 state, leads exclusively to production of I. Based on data from this study, an upper limit for the conical intersection between the 3Q0 and 1Q1 potential surfaces is ∼30 500 cm-1. [ABSTRACT FROM AUTHOR]