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Chemistry and dynamics of NO/sub 3/ produced by photolysis of N/sub 2/O/sub 5/. [NO/sub 3/]

Technical Report ·
OSTI ID:5413140
The results of several different studies involving the nitrate radical (NO/sub 3/) are reported in this work. The method of Flash Photolysis/Laser Absorption was used to measure directly the quantum yield for NO/sub 3/ production from UV photolysis of N/sub 2/O/sub 5/. Several product channels are possible at UV wavelengths. Although previous indirect studies indicated that the major products were 2 NO/sub 2/ + O, this work has shown that NO/sub 3/ is a primary product. The quantum yield of NO/sub 3/ obtained for photolysis at 249 nm was 0.90 +- 14 independent of pressure and N/sub 2/O/sub 5/ concentration. A fast rise in the concentration of NO/sub 3/ was observed which was dependent on both pressure and N/sub 2/O/sub 5/ concentration. The rate constants obtained for the deactivation process NO/sub 3/(nu > 0) + M ..-->.. No/sub 3/(nu = 0) + M were k(N/sub 2/O/sub 5/) = 4.0 +- 1.0 x 10/sup -12/ cm/sup 3/sec/sup -1/ and k(N/sub 2/) = 1.6 +- 0.3 x 10/sup -13/ cm/sup 3/sec/sup -1/. The structure of NO/sub 3/ was investigated by ab initio calculational methods. Geometry optimization gave a /sup 2/B/sub 2/ ground state of C/sub 2v/ symmetry with N-O bond distances R/sub 1/ = 1.34A, R/sub 2,3/ = 1.18A and unique angle THETA = 132/sup 0/. This structure was found to be 33.6 kcal/mole lower in energy than the optimized D/sub 3h/ structure (R = 1.21A). Calculated vibrational frequencies were consistent with those recently observed experimentally. 52 refs., 31 figs., 22 tabs.
Research Organization:
Lawrence Berkeley Lab., CA (USA)
DOE Contract Number:
AC03-76SF00098
OSTI ID:
5413140
Report Number(s):
LBL-20043; ON: DE85017657
Country of Publication:
United States
Language:
English