Van der Waals stretching and bending force constants from the rotational spectrum of argon… 1,3,5-trioxane

Abstract

The rotational spectrum of the argon… 1,3,5-trioxane van der Waals molecule has been observed by using pulsed-nozzle, Fourier-transform, microwave spectroscopy. The ground vibrational state rotational constant of this symmetric-top, semirigidrotor molecule leads to R = 363 pm for the distance of the argon atom from the centre of mass of 1,3,5-trioxane along the C3 axis. The quadratic force constant and wavenumber for the vibration corresponding to the stretching of R have been obtained from the centrifugal distortion constant DJ as kR = 1.96 Nm−1 and ωR = 35 cm−1. The combination of the centrifugal distortion constants DJK + 2DJ leads to the analogous quantities kα = 8.52 × 10−21 J and ωα = 14 cm−1 for the degenerate bending vibration corresponding to the orientation of R with respect to the C3 axis of the 1,3,5-trioxane molecule.