VIBRATIONAL STRUCTURE OF THE AR-NO-DER-WAALS CATION( VAN)

We report two different assignments of the vibrational structure of th e Ar-NO+ cation observed by Takahashi. On one hand, the ab initio pote ntial energy surface (PES) of Robbe et al. (Chem. Phys. Letters 210 (1 993) 170) allows us to interpret the main observed features as arising from a Fermi-type interaction between the stretching progression (v(s ), v(b) = 0) and the (v(s) - 1, v(b) = 2) combination band. On the oth er hand, the more recent ab initio PES of Wright et al. (J. Chem. Phys . 100 (1994) 5403) allows us to interpret this structure as arising fr om a Fermi-type interaction between the stretching progression (v(s), v(b) = 0) and two bending combination bands, namely (v(s) - 1, v(b) = 0) and (v(s) - 2, v(b) = 3). Only a subsequent intensity analysis coul d help decide between these two interpretations.