Rotational spectra of the Xe-(H2O)(2) van der Waals trimer: Xenon as a probe of electronic structure and dynamics

摘要

Rotational spectra of three isotopomers of the Xe-(H2O)(2) van der Waals trimer were recorded using a pulsed-nozzle, Fourier transform microwave spectrometer. Nine [nine, four] a-type and twelve [eleven, seven] b-type transitions were measured for the Xe-132-(H2O)(2) [Xe-129-(H2O)(2), Xe-131-(H2O)(2)] isotopomer. The determined rotational and centrifugal distortion constants were used to extract information about the structure and vibrational motions of the complex. The nuclear quadrupole hyperfine structures due to the Xe-131 (nuclear spin quantum number I = (3)/(2)) nucleus were also detected. The large value of the off-diagonal nuclear quadrupole coupling constant chi(ab) in particular provides detailed insight into the electronic environment of the xenon atom and the orientations of the water molecules within the complex. An effective structure that best reproduces the experimental Xe-131 nuclear quadrupole coupling constants is rationalized by ab initio calculations. An overall goal of this line of work is to determine how the successive solvation of a xenon atom with water molecules affects the xenon electron distribution and its intermolecular interactions. The results may provide molecular level interpretations of Xe-129 NMR data from, for example, imaging experiments.