Resonant multi-photon ionization spectra of three fluorotoluene- argon complexes through the S1←S0 transition are observed, using resonant multi-photon ionization, together with time-of-0flight mass spectrometry, in supersonic molecular beam. By the spectra analysis and theory calculation, the stretching vibrational frequencies and two bending vibrational frequencies of the three complexes are obtained. The results show after F atom and methyl group CH3 substitute H atom in benzene ring, their relative position has very little influence on the stretch vibration of the complexes, but strong effect on bending vibration. In addition in the complexes, Ar atom has apparent obstruction to the internal rotation of the methyl group.

Key words: ARGON, BENZENE P, PHOTOIONIZATION, MOLECULAR VIBRATION