Determining Accurate Kinetic Parameters of Potentially Important Heterogeneous Atmospheric Reactions on Solid Particle Surfaces with a Knudsen Cell Reactor

Autor:	G. M. Underwood, P. Li, and C. R. Usher, Vicki H. Grassian
Rok vydání:	2000
Předmět:	Chemistry Analytical chemistry Carbon black Mineral dust Kinetic energy medicine.disease_cause Fick's laws of diffusion Soot Chemical kinetics Chemical physics medicine Particle Gaseous diffusion Physical and Theoretical Chemistry
Zdroj:	The Journal of Physical Chemistry A. 104:819-829
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp9930292
Popis:	One of the most important applications of the Knudsen cell reactor is in determining heterogeneous reaction kinetics of potentially important atmospheric reactions. Knudsen cell measurements involving gas reactions on atmospherically relevant particle surfaces, including salt, carbon black, soot, and mineral dust, are often obtained using powdered samples. In this study, we have investigated the importance of gas diffusion into the underlying layers of powdered samples when determining kinetic parameters from Knudsen cell experiments. In particular, we show that the use of the geometric surface area of the sample holder is, in general, not justified in determining initial uptake coefficients or reaction probabilities because the interrogation or probe depth of gas-phase molecules into the bulk powder can be anywhere from tens to thousands of layers deep. One problem encountered by current models used to account for gas diffusion into the underlying layers is that the diffusion constant of the gas through ...
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::9252d8178096e6014031d273d04edae0 https://doi.org/10.1021/jp9930292 Zobrazit plný text záznamu