Spectroscopy and Spectral Analysis, Volume. 31, Issue 3, 604(2011)

Study of the Energy Transfer between Excited Rb2 and H2 Using the CARS Technique

CAI Qin*, ZHANG Li-ping, LUAN Nan-nan, DAI Kang, and SHEN Yi-fan
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    Using the CARS (coherent anti-Stokes Raman spectroscopy) detection technique, the authors investigated the electronic-to-rovibrational levels energy transfer between electronically excited Rb2 and H2. In this CARS experiment, the S-branch (Δν=1, ΔJ=2) transition of H2 was excited by two laser pulses, the pump and the Stokes, respectively, centered at 532 and 690 nm. The internal state distribution of collisionally populated H2 was probed. The scanned CARS spectra reveal that during energy transfer processes H2 molecules were produced only at the ν=1, J=1,2 and ν=2, J=0,1,2 rovibrational levels. From scanned CARS spectral peaks the population ratios were obtained. The n1/n5, n2/n5, n3/n5 and n4/n5 are 3.57±0.71, 2.65±0.53, 3.00±0.60 and 0.93±0.17, respectively, where n1, n2, n3, n4 and n5 represent the number densities of H2 at the rovibrational levels (2,0), (2,1), (2,2), (1,1) and (1,2), respectively. The population ratios indicate that the H2 molecules produced by the energy transfer process are 83% populated at the ν=2 vibrational level and 17% at ν=1. The relative fractions (〈fV〉∶〈fR〉∶〈fT〉= of average energy disposal were derived as (0.48, 0.01, 0.51), with major translational and vibrational energy release. Through semilog plot of the time-resolved CARS profiles under a simple kinetic model under the experimental conditions of T=573 K and P=5×103 Pa, the collisional transfer rate coefficients k12=(3.1±0.6)×10-14 cm-3·s-1 and k2=(4.9±1.0)×10-15 cm-3·s-1 have been obtained.

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    CAI Qin, ZHANG Li-ping, LUAN Nan-nan, DAI Kang, SHEN Yi-fan. Study of the Energy Transfer between Excited Rb2 and H2 Using the CARS Technique[J]. Spectroscopy and Spectral Analysis, 2011, 31(3): 604

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    Paper Information

    Received: Apr. 27, 2010

    Accepted: --

    Published Online: Aug. 16, 2011

    The Author Email: Qin CAI (caiqin1986320@sina.com)

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