Rovibronic bands of the A (2)B2 <-- X (2)B1 transition of C6H5O and C6D5O detected with cavity ringdown absorption near 1.2 microm.
We recorded several rovibronic bands of C(6)H(5)O and C(6)D(5)O in their A (2)B(2)<--X (2)B(1) transitions in the range 1.14-1.31 microm 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 (2)B(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 C(6)H(5)O, and nu(12)=772, nu(13)=626, nu(14)=365, nu(15)=812, nu(17)=599, nu(18)=532, and nu(19)=436 for C(6)D(5)O. Transitions involving vibrationally excited levels of nu(20) were also observed; nu(20) of the A state is greater by 50 cm(-1) than the X state of C(6)H(5)O. A weak origin at 7681 cm(-1) for the A<--X transition of C(6)H(5)O (7661 cm(-1) for C(6)D(5)O) with a c-type contour was observed. Observed isotopic ratios of vibrational wavenumbers for the A state of C(6)H(5)O to those of C(6)D(5)O are in good agreement with the predictions from quantum-chemical calculations at the B3LYP/aug-cc-pVTZ level.
Cheng
Chi-Wen
CW
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001, Ta-Hsueh Rd., Hsinchu 30010, Taiwan.
Witek
Henryk
H
Lee
Yuan-Pern
YP