title: Assignment of the Fundamental Modes of Hydroxyacetone Using Gas-Phase Infrared, Far-Infrared, Raman, and ab Initio Methods: Band Strengths for Atmospheric Measurements.
abstract: Hydroxyacetone (acetol) is a simple organic molecule of interest in both the astrophysical and atmospheric communities. It has recently been observed in biomass burning events and is a known degradation product of isoprene oxidation. However, its vibrational assignment has never been fully completed, and few quantitative data are available for its detection via infrared spectroscopy. Our recent acquisition of both the pressure-broadened gas-phase data and the far-IR spectra now allow for unambiguous assignment of several (new) bands. In particular, the observed C-type bands of several fundamentals (particularly in the far-infrared) and a few combination bands demonstrate that the monomer is in a planar (Cs) conformation, at least a majority of the time. As suggested by other researchers, the monomer is a cis-cis conformer stabilized by an intramolecular O-H···O═C hydrogen bond forming a five-membered planar ring structure. Band assignments in the Cs point group are justified (at least for a good fraction of the molecules in the ensemble) by the presence of the C-type bands. The results and band assignments are well confirmed by both ab initio MP2-ccpvtz calculations and GAMESS (B3LYP) theoretical calculations. In addition, using vetted methods for quantitative measurements, we report the first IR absorption band strengths of acetol (also in electronic format) that can be used for atmospheric monitoring and other applications.
authors.affiliation: Pacific Northwest National Laboratory , Richland, Washington 99354, United States.
authors.forename: Rodica
authors.initials: R
authors.lastname: Lindenmaier
authors.affiliation: A. R. Smith Department of Chemistry, Appalachian State University , Boone, North Carolina 28618, United States.
authors.forename: Nicole
authors.initials: N
authors.lastname: Tipton
authors.affiliation: Pacific Northwest National Laboratory , Richland, Washington 99354, United States.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sams
authors.affiliation: Pacific Northwest National Laboratory , Richland, Washington 99354, United States.
authors.forename: Carolyn S
authors.initials: CS
authors.lastname: Brauer
authors.affiliation: Pacific Northwest National Laboratory , Richland, Washington 99354, United States.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Blake
authors.affiliation: A. R. Smith Department of Chemistry, Appalachian State University , Boone, North Carolina 28618, United States.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Williams
authors.affiliation: Pacific Northwest National Laboratory , Richland, Washington 99354, United States.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Johnson