Photoenhanced uptake of gaseous NO2 on solid organic compounds: a photochemical source of HONO?

C. George (1) , Rafal Strekowski (2) , J. Kleffmann (3) , K. Stemmler (4) , M. Ammann (5)

1 CARE - IRCELYON-Catalytic and Atmospheric Reactivity for the Environment
2 LCE - Laboratoire Chimie de l'environnement
3 Physikalische Chemie/FB C
4 Laboratory of Radio- and Environmental Chemistry
5 PSI - Paul Scherrer Institute

This submission was created using the RSC Article Template (DO NOT DELETE THIS TEXT) (LINE INCLUDED FOR SPACING ONLY-DO NOT DELETE THIS TEXT) In several recent field campaigns the existence of a strong daytime source of nitrous acid was demonstrated. The mechanism of this source remains unclear. Accordingly, in the present laboratory study, the effect of light (in the range 300-500nm) on the uptake kinetics of NO2 on various surfaces taken as proxies for organic surfaces encountered in the troposphere (as organic aerosol but also ground surfaces) was investigated. In this collaborative study, the uptake kinetics and product formation rate were measured by different flow tube reactors in combination with a sensitive HONO instrument. Uptake on phenolic species was significantly enhanced when irradiated with light of 300 – 420 nm, and HONO was formed with high yield when the gas was humidified. Adding a stronger absorber, such as BBA, further enhanced the reactivity of the substrate. Based on the results reported a mechanism is suggested, in which photosensitised electron transfer are occurring. The results show that HONO can be efficiently formed during the day in the atmosphere at much longer wavelengths compared to the recently proposed nitrate photolysis.

Domaines: Chimie; Chimie analytique; Sciences de l'environnement

C. George, Rafal Strekowski, J. Kleffmann, K. Stemmler, M. Ammann. Photoenhanced uptake of gaseous NO2 on solid organic compounds: a photochemical source of HONO?. Faraday Discussions, 2005, 130, ⟨10.1039/b417888m⟩. ⟨hal-01784944⟩