Photodecomposition reaction of trapped aniline cation by photofragment excitation spectroscopy

A photofragment excitation spectrum of aniline cation, C 6 H 5 NH 2 + , was measured in the range of 450–400 nm by ion-trap mass spectrometry. The trapped cations exposed to a nanosecond laser field (I ≈ 1 MW/cm2, Δt ≈ 10 ns) absorbed two photons and dissociated into C 5 H 6 + efficiently in the 427–417 nm range. From a comparison with the photoelectron spectrum of neutral aniline, it is identified that the photodissociation of aniline cation into C 5 H 6 + proceeds via the second electronically excited ( B ˜ 2 B 1 ) state.