Knowledge Bank

Rotational transitions were measured for 5 isotopomers of HCCH-CO van der Waals complex using a Flygare-Balle type microwave spectrometer. The observed spectrum is consistent with a linear, hydrogen bound HCCH-CO structure. Measured rotational constants, in MHz are B=1397.370(1) for HCCH-CO, 1394.963(1) for HCCD-CO, 1385-142(1) for $HCCH-13CO$, $1331.23(1)$ for $DCCH-CO$ and $1329.684(2)$ for $DCCD.CO$. The measured rotational constants were fit to obtain a center of mass separation for HCCH-CO of $Rtm=5.018(7)$ \AA and a vibrationally averaged 0 $\approx 21\circ$ which corresponds to the motion of the HCCH about $Rtm$ in the complex. Distortion constants were obtained and analysed to obtain force constants and estimate the dissociation energies for the isotopomers.