Free and pulsed jet rotational spectra and van der Waals motions of ethanol⋯argon

The rotational spectrum of the ethanol⋯argon van der Waals complex has been investigated by free-jet absorption millimeter-wave and molecular beams Fourier transform microwave spectroscopy. The spectra of normal and OD isotopomers have been assigned, but only for the complex with trans-ethanol. ions produce vibrational splittings of 1.6662(7) and 1.70(2) MHz for the two isotopic species, respectively. The barrier hindering the tunnelling motion has been evaluated to be about 55 cm−1. n der Waals structural parameters are: r0(Ar–O) = 3.56(1) Å, α0(∠ArOC) = 94°(1) and τ0(∠ArOCC) = 71°(1). ssociation energy, as obtained from centrifugal distortion effects, is 2.1 kJ mol−1.