Temperature dependent rate coefficient for the reaction O(P-3)+NO2 -> NO+O-2

The rate coefficient (k(1)) for the reaction O(P-3) + NO2 --> O-2 + NO was measured under pseudo-first-order conditions in O(P-3) atom concentration o ver the temperature range 220-412 K. Measurements were made using pulsed la ser photolysis of NO2 to produce oxygen atoms and time-resolved vacuum UV r esonance fluorescence detection of O atoms. The NO2 concentration was measu red using three techniques: flow rate, UV absorption, and chemical titratio n (NO + O-3 --> NO2 + O-2) The NO2 UV absorption cross section at 413.4 nm was determined as a function of temperature using the chemical titration an d flow methods. Including the low-temperature data of Harder et al.(1), the temperature-dependent NO2 cross section is given by sigma(413.4)(T) (9.49 - 0.00549 T) x 10(-19) cm(2) molecule(-1). The measured rate coefficients f or reaction 1 can be expressed as k(1)(T) = (5.26 +/- 0.60) x 10(-12) exp[( 209 +/- 35)/T] cm(3) molecule(-1) s(-1), where the quoted uncertainties are 2 sigma and include estimated systematic errors. This result is compared w ith previously reported measurements of k(1).