MULTIPHOTON IONIZATION MECHANISMS IN CH3I AND CD3I

The processes that occur subsequent to the absorption of multiple phot ons by CH3I and CD3I in the 325-335 nm region have been studied using a single stage time-of-flight mass spectrometer. At the fluences emplo yed, ionization of methyl iodide, at parent resonances that were studi ed, can compete with parent fragmentation and subsequent ionization of the photofragments. The predominant source of the I+, CD2+, CD+, and C+ signals observed in the wavelength region under study is fragmentat ion of the methyl iodide parent ion. A similar mechanism is likely for CH3I.