Modeling Studies of Inhomogeneity Effects during Laser Flash Photolysis Experiments: A Reaction–Diffusion Approach
| Autor: | Gábor Lente, Éva Dóka |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Work (thermodynamics)
Partial differential equation Finite volume method 010405 organic chemistry Chemistry Analytical chemistry 010402 general chemistry Laser 01 natural sciences Molecular physics 0104 chemical sciences law.invention law Reaction–diffusion system Flash photolysis Light beam Physical and Theoretical Chemistry Diffusion (business) |
| Zdroj: | The Journal of Physical Chemistry A. 121:2740-2747 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/acs.jpca.7b00443 |
| Popis: | This work presents a rigorous mathematical study of the effect of unavoidable inhomogeneities in laser flash photolysis experiments. There are two different kinds of inhomegenities: the first arises from diffusion, whereas the second one has geometric origins (the shapes of the excitation and detection light beams). Both of these are taken into account in our reported model, which gives rise to a set of reaction-diffusion type partial differential equations. These equations are solved by a specially developed finite volume method. As an example, the aqueous reaction between the sulfate ion radical and iodide ion is used, for which sufficiently detailed experimental data are available from an earlier publication. The results showed that diffusion itself is in general too slow to influence the kinetic curves on the usual time scales of laser flash photolysis experiments. However, the use of the absorbances measured (e.g., to calculate the molar absorption coefficients of transient species) requires very detailed mathematical consideration and full knowledge of the geometrical shapes of the excitation laser beam and the separate detection light beam. It is also noted that the usual pseudo-first-order approach to evaluating the kinetic traces can be used successfully even if the usual large excess condition is not rigorously met in the reaction cell locally. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|