Resonant two-photon ionization spectra of fluorotoluene-argon complexes

The S-1 <-- S-0 transitions of three jet-cooled fluorotoluene-argon complexes are studied by the resonant two-photon ionization technique coupled with time-of-flight mass spectrometry. Detailed spectral analysis assisted by model calculations has allowed us to determine the stretching vibrational frequencies and two bending vibrational frequencies of the complexes. The results show that, the relative positions of the substituents (i.e., F and CH3) have very little influence on the stretching vibrations of the complexes but strongly affect their bending vibrations. In addition, the Ar atom is found to influence the internal rotation of the methyl group in the complexes. (C) 2003 Elsevier Science B.V. All rights reserved.