Knowledge Bank

In addition to the rotational spectrum of Ar-$HCO+$ reported $previouslym$, that of Kr-$HCO+$ was observed for the first time by using a PDN-FTMW spectroscopy. The complex was produced in a supersonic jet by discharging a mixture containing $H2$, CO, and Kr diluted in Ar. Rotational transitions of mono-substituted species on Kr, H, C, and O were also observed, yielding a precise substitution structure of the complex, where however a large amplitude bending motion of the complex had to be considered. The determined Rg-H distances were explained for species by considering a charge induced dipole-charge interaction. Furthermore, for Ar-$HCO+$, the Ar-H distance and the vibrational frequencies of the van der Waals modes, which were extimated by the centrifugal distortion constant and an analysis of the large amplitude bending motion, were in good agreement with a recent {ab initio} $calculationn$.