Molecular activation with low-intensity CW infrared laser radiation. Multiphoton dissociation of ions derived from diethyl ether

Multiphoton dissociation of gas-phase ions derived from (C/sub 2/H/sub 5/)/sub 2/O, (C/sub 2/D/sub 5/)/sub 2/O, and C/sub 2/H/sub 5/OC/sub 2/D/sub 5/ using low-intensity infrared CO/sub 2/ laser radiation is reported. Techniques of ion cyclotron resonance (ICR) spectroscopy are used to store ions, allowing irradiation for up to 2 s with intensities of 1-100 W cm-/sup 2/. Reasonably uniform irradiation of the stored ions is achieved with an unfocused laser beam facilitating studies of ion photodissociation kinetics. Decay of the ion population is characterized by an induction period followed by exponential decrease in ion abundance. The induction period is inversely proportional to laser irradiance with the product of these quantities yielding a fluence threshold for the reaction studied. Measured energy fluence thresholds and dissociation rate constants are comparable to data derived from pulsed laser experiments. For all ions which photodissociate only the decomposition process of lowest activation energy is observed. Detailed studies of the effects of collisions on the multiphoton dissociation of the proton-bound dimer ((C/sub 2/H/sub 5/)/sub 2/O)/sub 2/H/sup +/ are reported.