DETERMINATION OF THE STRUCTURE OF Ar H2CO

Abstract

The rotational spectrum of the weakly bound complex $Ar H_{2}CO$ has been measured using a pulsed beam Fourier transform microwave spectrometer. The rotational constants of the complex are $A-40059.939, MHz B=2174.588 MHz$, and $C=2080.318 MHz$. The argon atom sits almost directly above the carbon atom of the formaldehyde with an Ar--C distance of 3.66 A and an Ar--C-O angle of $86^{\circ}$. It is likely that the hydrogen atoms of the formaldehyde execute hindered internal rotation about the C-O axis and thus their positions within the complex are not well specified.