$^{131}xe$ NUCLEAR QUADRUPOLE COUPLING IN xeHCl

Author Institution:Rotational spectra have been observed for the $^{131}XeH^{35}Cl$, $^{129}XeH^{37}Cl$, $^{129}XeD^{35}Cl$ and $^{132}XeH^{35}Cl$ van der Waals molecules by employing pulsed microwave Fourier transform spectroscopy in a Fabry-Perot cavity with a pulsed supersonic nozzle as the molecular source. From the spectrum of $^{131}XeH^{35}Cl$ as well as from an analysis of the centrifugal distortion in $^{129}XeH^{35}Cl$ and $^{131}XeH^{35}Cl$ , the $^{131}Xe$ nuclear quadrupole coupling constant is found to be $-5.1 \pm 0.4$ MHz. using the known nuclear quadrupole moment of $^{131}Xe$, the electronic field gradient at the $^{131}Xe$ nucleus is calculated. The observed field gradient is discussed in terms of Sternheimer antishielding and the formation of the weal Xe-HCl van der Waals bond