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Fourier transform infrared spectroscopy of the NO/sub 3/ nu/sub 2/ and nu/sub 3/ bands: absolute line strength measurements

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100295a015· OSTI ID:6510102
The nitrate radical, NO/sub 3/, was produced in a low pressure (<10 Torr) discharge flow reactor and probed by high-resolution (0.005 cm/sup -1/) Fourier transform infrared spectrometry in the regions 730-780, 1020-1090, and 1470-1520 cm/sup -1/. Two infrared bands, consisting of only K/sup 2/ = 3n (n = integer) transitions, have been observed and are assigned, according to D/sub 3h/ symmetry, to the out-of-plane bend (nu/sub 2/) and to the N-O degenerate stretch (nu/sub 3/). Consistent with this assignment is the absence of a symmetric stretching band. Rovibrational constants are derived from the nu/sub 2/ band (nu/sub 0/ = 762.327 cm/sup -1/). Absolute NO/sub 3/ concentrations, derived from measured absorptions of helium-neon laser radiation (632.8 nm), are used in conjunction with the infrared measurements to determine absolute infrared line strengths. Band strengths for nu/sub 2/ and nu/sub 3/ of 26 +/- 19 and 150 +/- 100 cm/sup -2/ atm/sup -1/ are calculated from the observed line strengths. In addition, an upper limit of 2 cm/sup -2/ atm/sup -1/ is obtained for the band strength of the forbidden symmetric stretch (nu/sub 1/). These observed bands are not sufficiently intense to permit infrared detection of NO/sub 3/ in the terrestrial atmosphere using currently available techniques.
Research Organization:
California Institute of Technology, Pasadena
OSTI ID:
6510102
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:11; ISSN JPCHA
Country of Publication:
United States
Language:
English