VIBRONIC STRUCTURE IN TRIATOMIC-MOLECULES - THE HYDROCARBON FLAME BANDS OF THE FORMYL RADICAL (HCO) - A THEORETICAL-STUDY

A theoretical study of the vibrational structure of the (X) over tilde (2)A' pound and (B) over tilde(2)A' excited states of the formyl radic al, HCO, and its deuterated form, DCO, has been performed. The potenti al energy surfaces have been computed by means of a multiconfiguration al perturbative method, CASPT2. The computed geometries and the harmon ic and anharmonic frequencies are successfully compared to the availab le experimental information. The vibrational intensities of the transi tion (B) over tilde(2)A'<->(X) over tilde(2)A' have been computed both for absorption and emission. The results lead to accurate determinati ons of several structural parameters and some reassignments of the vib rational transitions of the so-called hydrocarbon flame bands of the f ormyl radical. (C) 1998 American Institute of Physics.