Vibronically resolved laser photoacoustic spectra of I2 vapor have been recorded at room temperature in the presence and absence of atmospheric air in the 490–680 nm (20402-14700 cm-1) region for what is, to our knowledge, the first time. The vibrational bands belong to the B3Π(Ou+) ← X1Σg+ transition, but the underlying continuum also results from the 1Π1u ← X 1Σg+ and A 3Π1u ← X 1aΣg+ transitions. The mechanisms of photoacoustic signal generation are discussed by analyzing the photoacoustic intensity in light of Franck-Condon factors for the B ← X transition. Energy transfer to O2 caused by the photodissociation of I2 into 2P⅔ + 2P½ I atoms is obrved in the presence of atmospheric air, and the predissociation of the B state has been observed for its vibrational levels v’ ~ 23–27.
© 1992 Optical Society of America
K. Narayanan and S. N. Thakur, "Photoacoustic spectrum of iodine in the 490–680-nm (20402-14700-cm-1) region," Appl. Opt. 31, 4987-4994 (1992)