1. OH, HO2, and Ozone Gaseous Diffusion Coefficients.
- Author
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Andrey V. Ivanov, Sofia Trakhtenberg, Allan K. Bertram, Yulii M. Gershenzon, and Mario J. Molina
- Subjects
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DIFFUSION , *OZONE , *CHEMICAL ionization mass spectrometry , *PRESSURE - Abstract
The diffusion of OH, HO2, and O3in He, and of OH in air, has been investigated using a coated-wall flow tube reactor coupled to a chemical ionization mass spectrometry. The diffusion coefficients were determined from measurements of the loss of the reactive species to the flow tube wall as a function of pressure. On the basis of the experimental results, DOH−He662 ± 33 Torr cm2s-1, DOH-air165 ± 20 Torr cm2s-1, DHO2-He430 ± 30 Torr cm2s-1, and DO3-He410 ± 25 Torr cm2s-1at 296 K. We show that the measured values for OH and HO2are in better agreement with measured values of their polar analogues (H2O and H2O2) compared with measured values of their nonpolar analogues (O and O2). The measured value for OH in air is 25% smaller than that for O (the nonpolar analogue). The difference between the measured value for HO2and O2(the nonpolar analogue) in air is expected to be even larger. Also we show that calculations of the diffusion coefficients based on Lennard−Jones potentials are in excellent agreement with the measurements. This gives further confidence that these calculations can be used to estimate accurate diffusion coefficients for conditions where laboratory data currently do not exist. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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