Laser-induced fluorescence excitation spectrum and radiative lifetime of Cl2+

Abstract

Laser-induced fluorescence from the Cl₂⁺ molecular ion has been observed for the first time and the excitation spectrum of the A(²Π_u)–X(²Π_g) transition recorded at rotational resolution. Although the rotational structure is regular, the vibrational levels of the upper state are heavily perturbed by an unknown state which has not been observed in emission experiments. A number of new bands are detected in this work which are assigned to transitions involving this previously unobserved perturbing state. The ions are generated in a supersonic free jet using a pulsed discharge technique and are observed in the collision-free region of the expansion. Substantial variation in the collision-free radiative lifetimes are observed among the vibrational bands of both the A(²Π_u) state and in the perturbing state. This is explained by considering the substantial mixing that occurs between these two states.