Rotational contours of electronic and electronic-vibrational bands of carbazole complexes with water cooled in a supersonic jet

Abstract

The rotational contours of the bands corresponding to electronic and electronic-vibrational transitions of the fluorescence excitation spectrum of jet-cooled carbazole complexes with one, two, and three water molecules have been studied. For the carbazole-(H2O)1 complex, two bands with a spectral shift of 0.57 cm−1 were recorded under exposure to radiation with a spectral width of 0.08 cm−1 at the frequency of the purely electronic transition and some other electronic-vibrational transitions. This is caused by the tunnel effect. The intensities of the shifted low-frequency bands are threefold weaker than those of high-frequency bands due to different values of nuclear spin-statistical weights. In the carbazole-(H2O)2 and carbazole-(H2O)3 complexes, water molecules are combined into a chain by the hydrogen bond, and the two ends of the chain are hydrogen-bonded to the carbazole molecule. The principal axes I A and I B of the moments of inertia in carbazole-(H2O)3 have different orientation compared to the other complexes considered, and this leads to an increase in the intensity of the Q-branch.