Vibrationally mediated photodissociation of t-butyl hydroperoxide: Vibrational overtone spectroscopy and photodissociation dynamics

Journal Article · Thu Jun 01 00:00:00 EDT 1989 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.456343· OSTI ID:6180546

Likar, M D; Baggott, J E; Crim, F F

Vibrationally mediated photodissociation is a two-photon technique for studying the spectroscopy and photodissociation dynamics of highly vibrationally excited molecules. In these experiments, a highly vibrationally excited t-butyl hydroperoxide (t-BuOOH) molecule, prepared by excitation in the region of the third overtone of the O--H stretching vibration (4..nu../sub OH/), absorbs a second photon to dissociate to OH and t-butoxy fragments, and laser induced fluorescence determines the quantum state populations of the OH fragment. Vibrational overtone excitation spectra, obtained by varying the vibrational overtone excitation wavelength while monitoring a single OH rotational state, are nearly identical to photoacoustic spectra. We fit the coarse structure in the vibrational overtone excitation spectrum in the region of the 4..nu../sub OH/ transition and the photoacoustic spectra in the regions of the 5..nu../sub OH/ and 6..nu../sub OH/ transitions using a spectroscopic model of the interaction of the O--H bond stretching vibration with the torsional vibration about the O--O bond. This analysis determines the barrier to internal rotation of the O--H and t-butoxy groups through the trans configuration and its variation with vibrational excitation. The trans barrier in the ground vibrational state is 275 cm/sup -1/ and increases with vibrational excitation to 425, 575, and 680 cm/sup -1/ for t-BuOOH molecules with four, five, and six quanta of O--H stretching excitation, respectively.

• Research Organization: Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
• OSTI ID: 6180546
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 90:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALKOXY RADICALS
BUTOXY RADICALS
CHEMICAL BONDS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CONFORMATIONAL CHANGES
DECOMPOSITION
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
HYDROXYL RADICALS
MULTI-PHOTON PROCESSES
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADICALS
VIBRATIONAL STATES
YIELDS