The branching ratio in the infrared predissociation of aniline-water-methanol+ ion

The infrared (IR) photodissociation of aniline-water-methanol cluster ion was investigated in the 2600-3900 cm−1 region to examine the factors which play key roles in determining the branching ratio of a concurrent predissociation reaction. The dominant channel in the IR predissociation of AWM+ (A: aniline, W: water, M: methanol) was AWM+ → AM+ at all vibrational modes although the calculated binding energies of water and methanol were nearly the same. Also, the branching ratio was slightly dependent on the specific excited mode, ranging from 0.036 to 0.074; the most effective mode to kick out methanol was OH vibration of methanol.

33Research highlights► Aniline(water)(methanol)+ loses water, not methanol, upon absorption of an IR photon. ► Excitation of OH vibration of methanol facilitates ejection of methanol. ► Binding energy is not a crucial factor to determine the branching ratio. ► Number of modes of solvent molecules affects the branching ratio.