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+) ← X1∑g+ transition, but the underlying continuum also results from the 1Π1u ← X1∑g+ and A3Π1u ← X1a∑g+ 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 2P3/2 + 2P1/2 I atoms is observed 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
Original Manuscript: May 17, 1991
Published: August 20, 1992
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)