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X2A' TRANSITION OF ISOPROPOXY RADICAL: ISOLATED STATE vs. COUPLED STATES MODEL.
DMITRY G. MELNIK AND TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210; JINJUN LIU, Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292.
Isopropoxy radicals are reactive intermediates in atmospheric and combustion chemistry. From the theoretical point of view, they represent an extreme case of ``isotopically'' substituted methoxy radicals with two methyl groups playing the role of heavy hydrogen isotopes. Previously the rotationally resolved spectra of B2A'
X2A' electronic transition were successfully analyzed using a simple effective rotational Hamiltonian of the isolated X and B states. However, a number of the experimentally determined parameters appeared dramatically inconsistent with the quantum chemistry calculations and theoretical predictions based on the symmetry arguments.
Recently, we analyzed these spectra using a coupled two state model, which explicitly includes interactions between the ground X2A' state and low-lying excited A2A'' state. In this presentation we will discuss the results of this analysis and compare the parameters of both models and their physical significance.