Rovibronic bands of the (A)over-tilde B-2(2) -(X)over-tilde B-2(1) transition of C6H5O and C6D5O detected with cavity ringdown absorption near 1.2 mu m

摘要

We recorded several rovibronic bands of C6H5O and C6D5O in their (A) over tilde B-2(2)<-(X) over tilde B-2(1) transitions in the range 1.14-1.31 mu m with the cavity ringdown technique. While the electronic transition is forbidden, several vibronic bands are observed. By comparison of rovibronic contours of observed and simulated bands to determine their types of transition, and by consideration of vibrational wavenumbers of the upper state based on quantum-chemical calculations, we were able to provide vibronic assignments of observed bands and derive several experimental vibrational wavenumbers (given as nu in unit of cm(-1) in this paper) for the (A) over tilde B-2(2) state, namely, nu(12)=947, nu(13)=793, nu(14)=417, nu(15)=964, nu(16)=866, nu(17)=723, nu(18)=680, and nu(19)=499 for C6H5O, and nu(12)=772, nu(13)=626, nu(14)=365, nu(15)=812, nu(17)=599, nu(18)=532, and nu(19)=436 for C6D5O. Transitions involving vibrationally excited levels of nu(20) were also observed; nu(20) of the (A) over tilde state is greater by 50 cm(-1) than the (X) over tilde state of C6H5O. A weak origin at 7681 cm(-1) for the (A) over tilde <-(X) over tilde transition of C6H5O (7661 cm(-1) for C6D5O) with a c-type contour was observed. Observed isotopic ratios of vibrational wavenumbers for the (A) over tilde state of C6H5O to those of C6D5O are in good agreement with the predictions from quantum-chemical calculations at the B3LYP/aug-cc-pVTZ level. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2992077]