High-resolution UV spectrum of the benzene—N 2 van der Waals complex

Abstract

The rotationally resolved spectrum of the 6 1 0 band of the S 1 ← S 0 electronic transition of the benzene—N 2 van der Waals complex has been recorded and 119 transitions assigned. The C 6H 6·N 2 complex, produced in a pulsed molecular beam, was detected by mass-selected two-photon two-colour ionization employing a high-resolution (Δν UV = 100 MHz, fwhm) pulsed-amplified cw laser for the resonant intermediate excitation. The observed rotational structure is that of a rigid symmetric top with weaker additional rotational transitions most likely arising from the free internal rotation of the N 2 in the plane parallel to the benzene ring. The N 2 is located parallel to the benzene ring at a distance of 3.50 Å; this decreases by 45 mÅ in the excited electronic state.