PNNL

Abstract

Infrared absorption profiles observed for vibrational transitions of gaseous tropolone often show sharp Q branch peaks, some of them ultra-narrow spikes, indicative of the band origins for vibrational state-specific spectral tunneling doublets. In this work oxygen isotope effects for two CH wagging fundamentals, the COH torsion fundamental, and the skeletal contortion fundamental are reported. They allow considerations to be given: (1) oxygen isotope effects on the vibrational frequencies and state-specific tunneling splittings; (2) the asymmetry offset of the potential energy minima for 16O, 18O-tropolone; and (3) additional details concerning previously proposed high J rotation-contortion fundamental. The new results help to characterize the skeletal contortion fundamental and support the jo9nt participation of skeletal tunneling with H tunneling in the vibrational state-specific tautomerization processes of tropolone in its ground electronic state.