ANOMALOUS COMPLEX SHIFT OF LOW-FREQUENCY OUT-OF-PLANE VIBRATIONS IN ANILINE-M VAN-DER-WAALS COMPLEXES (M=HE, NE, AR)

Fluorescence excitation vibronic spectra of aniline-M (M=He, Ne, Ar) van der Waals (vdW) complexes have been measured in the spectral region from 300 to 500 cm(-1) above S-1 - S-0 origin. Anomalous behavior of the vdW shifts are observed for two out-of-plane vibrational modes. The resulting vdW vibrational shifts for the nu(16a) vibration are as large as 26.5 cm(-1). Similarity with shifts which have already been reported for other aromatic molecules, like pyrimidine [H. Abe, Y. Ohyanagi, M. Ichijo, N. Mikami, and M. Ito, J. Phys. Chem. 89, 3512 (1985)] and tetrazine [D. V. Brumbaugh; J. E. Kenney, and D. H. J. Levy, J. Chem. Phys. 78, 3415 (1983); P. M. Weber and S. A. Rice, J. Chem. Phys. 88, 6120 (1988)] are pointed out.