title: Analysis of the High-Resolution Rotational Structure of the Origin and First Torsional Members of the 267-nm Band System of Formic Acid.
abstract: The fluorescence excitation spectrum of formic acid monomer (HCOOH) was recorded in the 268-257 nm region under relatively high resolution. The cooling conditions of a rotating slit-jet nozzle simplified the rotational structure and allowed for a combination line-by-line least-squares/band-contour analysis and the determination of the rotational constants. The 0(0)(0) and 9(1)(0) bands were each simultaneously fitted to a combination of c-type and b-type bands. The coexistence of the two band types is a consequence of the very small separation between the 0(+) and 0(-) levels of the inversion mode, nu(8), brought about by the pyramidal conformation of the upper electronic state. In contrast, the 9(2)(0) band shows a splitting of 0.288 cm(-1) and is a consequence of the increased torsion-inversion coupling at higher energies. The 8(1)(0) band could only be approximately modeled using band-contour techniques with an estimated 1(+)-1(-) splitting of 0.5 cm(-1). The assignments, the observed, and calculated line positions used in the least-squares analyses are available in electronic form from the publisher as supplementary material. Copyright 2001 Academic Press.
authors.affiliation: Department of Chemistry, Brock University, St. Catharines, Ontario, L2S 3A1, Canada
authors.forename: Leanne M.
authors.initials: LM
authors.lastname: Beaty-Travis
authors.forename: David C.
authors.initials: DC
authors.lastname: Moule
authors.forename: Haisheng
authors.initials: H
authors.lastname: Liu
authors.forename: Edward C.
authors.initials: EC
authors.lastname: Lim
authors.forename: R. H.
authors.initials: RH
authors.lastname: Judge