QUANTUM YIELDS FOR OH PRODUCTION FROM 193 AND 248 NM PHOTOLYSIS OF HNO3 AND H2O2

The absolute quantum yields (PHI) for OH production from 193 and 248 n m photolysis of HNO3 and H2O2 are measured at room temperature using f lash kinetic spectroscopy in a flow tube. The OH radicals are produced by excimer laser photolysis and probed via direct absorption of high resolution, tunable IR laser light. The resulting quantum yields are f ound to be PHI193HNO3 = 0.47 +/- 0.06, PHI193H2O2 = 1.22 +/- 0.13, PHI 248HNO3 = 0.75 +/- 0.10, and PHI248H2O2 = 1.58 +/- 0.23 .These results indicate quantum yields for both precursors at both wavelengths which are less than the maximum possible values of 1 for HNO3 and 2 for H2O 2. The present measurements are discussed in light of contrasting resu lts suggested from other work.