Molecular structure of p-methylaniline and its van der Waals complexes with CF3H, CH4 and CF4 studied by laser induced fluorescence spectroscopy and ab initio calculations

The UV fluorescence excitation and dispersed fluorescence spectra of jet-cooled p.-methylaniline have been obtained for the S-1 <-- S-0 transition. The main spectral bands have been assigned by comparison with those of other relevant substituted benzenes and with the help of computed vibrational frequencies. The structure of p-methylaniline in both the S-0 and S-1 states has been studied at ab initio quantum chemical calculations at MP2 and CIS levels of theory using the 6-31 + G(*) basis sets. Both low-and high-resolution laser induced fluorescence spectra of p-methylaniline van der Waals complexes with CF3H, CH4 and CF4 have been characterised following jet-expansion investigations. The equilibrium geometries in the ground state of the complexes have been calculated at MP2/6-31 + G(*) level of calculation and their rotational contour have been simulated for all the complexes studied. (C) 2002 Elsevier Science B.V. All rights reserved.