Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

HO2 + NO revisited first rate constants at tropospheric pressures

: Koch, R.

Mirabel, P. ; European Commission, Directorate-General for Science, Research and Development:
Homogeneous and heterogeneous chemical processes in the troposphere : Strasbourg, 25 and 26 September 1995
Luxembourg: Office for Official Publications of the European Communities, 1996 (Air pollution research report 57)
ISBN: 92-827-6147-9
Fraunhofer ITA ( ITEM) ()
air pollution; atmospheric chemistry; chemical reaction; flash photolysis; hydroxyl group; nitrogen oxide; OH radical; oxidation; photochemistry; physical chemistry; radical; rate constant; theoretical chemistry; troposphere

The rate constant of this reaction is required to model - in the atmosphere and in laboratory experiments - its competition with chain terminating reactions (HO2 + OH, HO2 + RO2) affecting the oxidation potential of the troposphere, and with other NO-consuming reactions (RO2 +NO): where NO is scarce, the product distribution depends on whether HO2 or RO2 reacts with NO. While the negative temperature dependence suggests also a pressure dependence, the current recommendation for this important reaction relies solely on low-pressure data from discharge flow experiments. In this work, i present flash photolysis/resonance fluorescence experiments (FP/RF) in the temperature range 254-422 K and up to 970 mbar He. Several tests showed both radical-radical reactions and background OH to be unimportant. The obtained OH kinetics is well described by a global fit (first-order rate constants constrained to be linear in NO).