The high-resolution far infrared spectrum of a van der Waals stretching vibration: The ν3 band of Ar–HCl

Abstract

The first high‐resolution measurement of a van der Waals stretching vibration is reported. The ν₃ fundamental stretching vibration in Ar–HCl has been measured by intracavity far infrared laser/microwave double resonance spectroscopy of a supersonic free jet. Coupling between the stretching state and the nearby bending states gives the spectrum an intensity which is greater than predicted. The molecular constants for the stretching state are in close agreement with calculations by Hutson for the M5 potential surface.