Vibrational predissociation of aniline-Inert gas cluster cations

• The ring isomer is more stable for PhNH2Ne+ and PhNH2Ar+ whereas the NH isomer is more stable for PhNH2Kr+.
• The rate of vibrational predissociation increases with increasing the size of the X in PhNH2X+.
• The vibrational predissociation of PhNH2X+ is a nonstatistical process.

The molecular structures and predissociation dynamics of aniline (Phenylamine, PhNH2)-inert gas cluster cations PhNH2X+ (X = Ne, Ar, and Kr) were investigated by infrared (IR) spectroscopy coupled with density functional theory (DFT) calculations and IR photofragmentation studies. The ring isomer was the minimum energy structure for PhNH2Ne+ and PhNH2Ar+ whereas the NH isomer was more stable in PhNH2Kr+. The decay constants of PhNH2X+ for ejection of X excited with IR depended strongly on the structure of PhNH2X+, presumably because the rate of intramolecular vibrational energy redistribution (IVR) was governed by the structure. As a result, the dissociation was faster for the larger PhNH2X+ clusters, because the rate of IVR was faster for the NH type structure than the ring type. The decay constants deviate from those expected from the Rice–Ramsperger–Kassel–Marcus (RRKM) theory calculation by the factors of 104 or larger, manifesting that the dissociation occurred mainly via nonstatistical pathways.

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