High-resolution UV spectrum of the benzeneN2 van der Waals complex
The rotationally resolved spectrum of the 610 band of the S1 \u2190 S0 electronic transition of the benzene\u2014N2 van der Waals complex has been recorded and 119 transitions assigned. The C6H6\xb7N2 complex, produced in a pulsed molecular beam, was detected by mass-selected two-photon two-colour ionization employing a high-resolution (\u0394\u03bdUV = 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 N2 in the plane parallel to the benzene ring. The N2 is located parallel to the benzene ring at a distance of 3.50 \xc5; this decreases by 45 m\xc5 in the excited electronic state.