The unimolecular dissociation of HCO: A spectroscopic study of resonance energies and widths

Journal Article · Sat Jul 22 04:00:00 EDT 1995 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.470699· OSTI ID:69444

Tobiason, J D; Dunlop, J R; Rohlfing, E A ^[1]

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1. Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551 (United States)

We use dispersed fluorescence (DF) and stimulated emission pumping (SEP) spectroscopies on the {ital {tilde B}} {sup 2}{ital A}{prime}--{ital {tilde X}} {sup 2}{ital A}{prime} system of jet-cooled HCO to measure the vibrational energies, resonance widths, and relative fluorescence intensities of 73 bound and resonance states supported by the ground-state potential energy surface. The SEP experiments use both two-color resonant four-wave mixing (RFWM-SEP) and the more conventional technique in which SEP signals are obtained from fluorescence depletion (FD-SEP). Where applicable, RFWM-SEP provides superior spectra to those obtained with FD-SEP, which is susceptible to saturation broadening that can prevent accurate determinations of resonance widths. The observed bound and resonance states span an energy range of 2000--21 000 cm{sup {minus}1} and comprise a wide range of vibrational excitation among the three vibrational modes, including states with 1--12 quanta of excitation in the C--O stretch, 0--5 quanta of bending excitation, and 0--1 quanta of excitation in the C--H stretch. The widths are markedly mode-specific and often display striking, nonmonotonic variations with increasing C--O stretch excitation. We compare our results to those of previous DF and SEP studies and to recent dynamical calculations of resonance energies and widths that use realistic potential surfaces derived from {ital ab} {ital initio} calculations. The resonance widths are particularly sensitive gauges of the unimolecular dissociation dynamics and provide stringent tests of theoretical potential surfaces. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

• OSTI ID: 69444
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 4 Vol. 103; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
66 PHYSICS
BOUND STATE
COMBUSTION
DISSOCIATION
ENERGY SPECTRA
ENERGY TRANSFER
FLUORESCENCE
FORMYL RADICALS
HYDROCARBONS
LINE WIDTHS
VIBRATIONAL STATES