Internal dynamics in SF6···NH3 observed by broadband rotational spectroscopy

Abstract

The rotational spectra of SF$_{6}$$cdot$$cdot$$cdot$NH$_{3}$ isotopologues have been observed in a pulsed nozzle chirped pulse Fourier-transform microwave spectrometer in the frequency range 6.5-18.5 GHz. The spectrum of SF$_{6}$$cdot$$cdot$$cdot$$^{14}$NH$_{3}$ has been fitted to a Hamiltonian describing a symmetric top complex in which two symmetric top subunits undergo free internal rotation about a common symmetry axis. The distance between the centers of mass of the two monomers was found to be 4.15776(7) AA. Challenges associated with fitting textbar textit{m}textbar =1 transitions (correlating with textit{K} of free NH$_{3}$) for SF$_{6}$$cdot$$cdot$$cdot$$^{14}$ND$_{3}$ imply complicated internal dynamics occurs within the complex.