title: Time resolved high frequency spectrum of Br2 molecules using pulsed photoacoustic technique.
abstract: The paper reports the time resolved spectral distribution of higher order acoustic modes generated in Br2 molecules using pulsed Photoacoustic (PA) technique. New time resolved vibrational spectrum of Br2 molecules are recorded using a single 532nm, pulses of 7ns duration at 10Hz repetition rate obtained from Q-switched Nd:YAG laser. Frank-Condon principle based assignments confirms the presence of 12 numbers of (ν″-ν') vibrational transitions covered by a single 532+2nm pulse profile. Inclusions of higher order zeroth modes in Bassel's function expansion series shows the probability of overlapping of different types of acoustic modes in the designed PA cells. These modes appear in the form of clusters which occupies higher frequency range. The study of decay behavior of PA signal with respect to time confirms the photolysis of Br2 at 532nm wavelength. In addition, the shifting and clustering effect of cavity eigen modes in Br2 molecules have been studied between 1 and 10ms time scale. The estimated Q-factor of PA cell (l=16cm, R=1.4cm) is 145±4 at 27kHz frequency.
authors.affiliation: Advanced Centre of Research in High Energy Materials, University of Hyderabad, Hyderabad 500 046, AP, India.
authors.forename: Fahem
authors.initials: F
authors.lastname: Yehya
authors.forename: A K
authors.initials: AK
authors.lastname: Chaudhary
mesh_terms: D000042:Absorption; D001966:Bromine / Q000737:chemistry*; D007834:Lasers; D061088:Photoacoustic Techniques; D013997:Time Factors
chemical_list: D001966:Bromine
keywords: Br(2); Clustering; Modes; Photoacoustic; Pulsed laser; Vibronic