Vibrational structure of the ArNO+ van der Waals cation Original Research Article

We report two different assignments of the vibrational structure of the ArNO+ cation observed by Takahashi. On one hand, the ab initio potential energy surface (PES) of Robbe et al. (Chem. Phys. Letters 210 (1993) 170) allows us to interpret the main observed features as arising from a Fermi-type interaction between the stretching progression (νs, νb = 0) and the (νs − 1, νb = 2) combination band. On the other 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 from a Fermi-type interaction between the stretching progression (νs, νb = 0) and two bending combination bands, namely (νs − 1, νb = 0) and (νs − 2, νb = 3). Only a subsequent intensity analysis could help decide between these two interpretations.