The Theoretical Basis of the Kinetic Method from the Point of View of Finite Heat Bath Theory

Autor:	Julia Laskin, Jean H. Futrell
Rok vydání:	2000
Předmět:	Chemical kinetics Reaction rate Entropy (classical thermodynamics) education.field_of_study Mathematical model Chemistry Population Thermodynamics Physical and Theoretical Chemistry Kinetic energy education Curvature Specific kinetic energy
Zdroj:	The Journal of Physical Chemistry A. 104:8829-8837
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp001556b
Popis:	We present a rigorous theoretical basis of the kinetic method, commonly used for thermochemical determinations in mass spectrometry, based on finite heat bath theory (FHBT) developed by Klots. A simple analytical expression for the branching ratio is derived from FHBT formalism. This expression simplifies to the expression given by the absolute reaction rate theory (1) for very large clusters or (2) for reactions having a negligible kinetic shift. The reacting population is described by two different temperatures rather than by the “effective” temperature as suggested previously. Simulations performed using both RRKM and FHBT revealed that the kinetic plots are slightly nonlinear. The observed curvature is related to the changes in the transition state temperature as a function of the critical energy for fragmentation. The curvature of the plots decreases for larger clusters. We show that the “effective” temperature closely resembles the average value of the transition state temperature. This allows us to...
Databáze:	OpenAIRE
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