Infrared spectroscopy of weakly bound complexes in superfluid helium nanodroplets

Abstract

The OH···CH4 complex has been isolated in superfluid helium nanodroplet matrices. The infrared spectrum in the region of the OH stretch (~3562 cm-1) has been collected. What should be single transitions as compared to the spectrum for the OH radical in superfluid helium are split into triplets. The origin of this splitting pattern is thought to be the K states of the internal rotor projected onto the intermolecular axis. Systematic deuteration allowed for the collection of three other isotoplogue specta: OD···CH4, OH···CD4, and OD···CD4. Splitting of lines belonging to the heaviest isotopologue are virtually non-existent. This provides an interesting opportunity to study the effects controlling the moment of inertia of a weakly bound complex can have on its ability to exhibit large amplitude motions. Current progress and a framework for future consideration is presented.