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A study of some elementary gas phase reactions

A study of some elementary gas phase reactions
A study of some elementary gas phase reactions

The infra-red chemiluminescence technique has been used to measure the initial disposal of energy among the products of the simple atommolecule reactions:(a) D + F2+ OF t + F(b) F + DBr + DFt + Br. The infra-red emission from these reactions was monitored by grating spectroscopy. The resultant deuterium fluoride spectra do not lend themselves to straightforward analysis. Consequently, it was necessary to develop a computer simulation technique for this purpose.In the case of each reaction, comparison has been made with the energy disposal in the isotopically analogous systems:(c) H + F2 + HFt + F (d) F + HBr - HFt + Br. In particular, new experiments have been devised in an attempt to resolve the controversy regarding the vibrational energy disposal in reaction (d). Two theoretical approaches have been employed in order to rationalize the microscopic rate constants obtained in this work: Firstly, the classical trajectory technique has been used to determine the semi-empirical. LEPS-type surface, which best reproduces the product vibrational population distribution. The finding that a common surface did not lead to the best description of the isotopically analogous pair of reactions (a) and (c), is suggested as being due to a particular limitation of the classical trajectory method. Secondly, information-theoretic analysis has been used in order to assess the deviation from statistical behaviour, due to dynamical constraints acting upon the system. Finally, a stochastic model for the unimolecular decomposition of a diatomic molecule in a heat bath gas, has been developed in order to account for the behaviour of polyatomic molecules. A single mode Monte Carlo model. which assumes that the heat bath gas atom interacts with a single vibrational mode of the polyatomic molecule, has been found to be capable of reproducing the equilibrium properties of a collection of polyatomic molecules. The model has been applied to a study of the unimolecular decomposition of H202, CHq, COq and C2H6 at low pressure. The technique has been further extended to include pressure dependent behaviour. In particular, the influence of adiabatic rotations and the role of the random lifetime assumption have been examined within this framework.

University of Southampton
Sellers, Patricia Veronica
Sellers, Patricia Veronica

Sellers, Patricia Veronica (1981) A study of some elementary gas phase reactions. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The infra-red chemiluminescence technique has been used to measure the initial disposal of energy among the products of the simple atommolecule reactions:(a) D + F2+ OF t + F(b) F + DBr + DFt + Br. The infra-red emission from these reactions was monitored by grating spectroscopy. The resultant deuterium fluoride spectra do not lend themselves to straightforward analysis. Consequently, it was necessary to develop a computer simulation technique for this purpose.In the case of each reaction, comparison has been made with the energy disposal in the isotopically analogous systems:(c) H + F2 + HFt + F (d) F + HBr - HFt + Br. In particular, new experiments have been devised in an attempt to resolve the controversy regarding the vibrational energy disposal in reaction (d). Two theoretical approaches have been employed in order to rationalize the microscopic rate constants obtained in this work: Firstly, the classical trajectory technique has been used to determine the semi-empirical. LEPS-type surface, which best reproduces the product vibrational population distribution. The finding that a common surface did not lead to the best description of the isotopically analogous pair of reactions (a) and (c), is suggested as being due to a particular limitation of the classical trajectory method. Secondly, information-theoretic analysis has been used in order to assess the deviation from statistical behaviour, due to dynamical constraints acting upon the system. Finally, a stochastic model for the unimolecular decomposition of a diatomic molecule in a heat bath gas, has been developed in order to account for the behaviour of polyatomic molecules. A single mode Monte Carlo model. which assumes that the heat bath gas atom interacts with a single vibrational mode of the polyatomic molecule, has been found to be capable of reproducing the equilibrium properties of a collection of polyatomic molecules. The model has been applied to a study of the unimolecular decomposition of H202, CHq, COq and C2H6 at low pressure. The technique has been further extended to include pressure dependent behaviour. In particular, the influence of adiabatic rotations and the role of the random lifetime assumption have been examined within this framework.

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Published date: 1981

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Local EPrints ID: 459559
URI: http://eprints.soton.ac.uk/id/eprint/459559
PURE UUID: f420bc24-d2f5-4266-bde0-714fc9000f2f

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Date deposited: 04 Jul 2022 17:14
Last modified: 04 Jul 2022 17:14

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Author: Patricia Veronica Sellers

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