ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Production of electronic ground state NO2 (2A1) from 248 nm photolysis of HNO3 was detected by laser induced fluorescence (LIF). A growth in the LIF signal was observed following the photolysis and has been interpreted as the relaxation of NO2 through the higher vibrational levels of the X(2A1) state; an energy region where the probe laser photodissociates the NO2 instead of inducing fluorescence. The rate coefficients for NO2 relaxation through these high vibrational levels were determined by fits of time resolved LIF signal to a stepladder kinetic model. The results of the kinetic analysis suggest that the observed relaxation begins at the 2B2 threshold near 9500 cm−1 and extends downward through approximately 5 vibrational levels of the ground electronic surface. The derived quenching rate coefficients (in units of 10−12 cm3 molecule−1 s−1) are 0.51±0.05, 1.0±0.1, 1.4±0.2, 2.6±0.6, and 8.7±1.1 for Ar, He, N2, O2, and CO2 collision partners, respectively. The discrepancies between these coefficients and previous literature values are rationalized in terms of a dependence of the vibrational relaxation rate on total internal energy.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.466797
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