Kinetic and mechanistic study of the F atom reaction with nitrous acid

The kinetics and mechanism of the reaction of nitrous acid (HONO) with F atoms have been studied using the mass spectrometric discharge-flow method at 298 K and at a total pressure of 130 Pa of helium. The rate coefficient of the reaction F+HONO→products (1) was measured under pseudo-first order conditions from the kinetics of HONO decay in excess of F atoms: k1=(5.4±1.1)×10−11 cm3 molecule−1 s−1 (quoted uncertainty includes estimated systematic errors). NO2 was detected as a product of reaction (1) and the reaction F+HONO→HF+NO2 (1a) was found to be the main (if not unique) channel of reaction (1) under the experimental conditions of the study (k1a/k1=1.0±0.1 (±2σ)). These results indicate that reaction (1) can be a suitable titration reaction for the measurements of the absolute HONO concentrations under laboratory conditions.