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The effect of collisions in the multiphoton decomposition of 1-bromo 2-fluoroethane (1990)

McRae, Glenn A. ; Evans, D. K. ; Goodale, J. W.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 93 (1990), S. 1689-1694

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ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The multiphoton decomposition (MPD) of 1-bromo 2-fluoroethane, CH2BrCH2F, with a pulsed CO2 infrared laser is reported. The decomposition study was done at constant fluence and at pressures up to 2 kPa. Empirical representations of the pressure dependence of the MPD are reported. A collision-dependent reaction scheme is presented to explain the pressure dependence of the up-pumping through the vibrational manifold.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.459096

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The effect of collisions in the multiphoton decomposition of chloroform-d (1990)

McRae, Glenn A. ; Yamashita, A. Brian ; Goodale, J. W.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 92 (1990), S. 5997-6003

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ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The multiphoton decomposition (MPD) of chloroform-d, CDCl3, with a pulsed 13CO2 infrared laser is reported. A new method is developed that takes into account the effect of the number of pulses required to obtain a measurable decomposition. This method relies on difference equations and replaces current methods based on differential calculus. The rate equation language of the latter is shown to be inappropriate. The decomposition probability is measured at constant fluence up to a pressure of 2 kPa and empirical representations of the pressure dependence of the MPD are reported. A collision-dependent reaction scheme is presented to explain the pressure dependence of the up-pumping through the vibrational manifold.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.458370

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Decomposition of highly vibrationally excited CDCl3 (1992)

Ivanco, M. ; McRae, G. A. ; Back, R. A. ; [weitere]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 96 (1992), S. 5191-5197

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ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: Decomposition of highly vibrationally excited CDCl3 was studied in the time domain by measuring laser-induced fluorescence from one of the decomposition products CCl2 or by observing luminescence from CCl2 radical fragments produced in the A˜(1B1) state following IR excitation. It is shown that highly vibrationally excited CDCl3 can be made via two different routes: i(Slashthrough accent mark)mple optical absorption of an incident 13CO2 laser pulse or through collision-moderated energy pooling coupled with photon absorption. Higher fluence measurements are consistent with the former and support previous claims that the infrared multiphoton decomposition probability for CDCl3 is pressure independent. At a lower fluence the vibrational up-pumping mechanism apparently relies heavily upon collisions, which supports other claims that the decomposition probability is pressure dependent. The results of the present work reconcile these previous disparate claims. Furthermore, there is an indication that the vibrational energy transferred during a collision could be much larger than collision-induced dipole selection rules would allow. In some of the experiments, electronically excited CCl2 fragments are created but only through post-laser-pulse collisions that appear to involve exchanges of very large amounts of vibrational energy. By contrast, no electronically excited CCl2 is produced following excitation with the CO2 laser alone. The experiments also corroborate an earlier prediction that the extent of reaction is governed by adiabatic expansion of the centrally heated zone, even at pressures as low as 0.66 kPa, rather than by diffusion, as is commonly believed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.462759

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Two-color multiphoton decomposition of 1-bromo 2-fluoroethaneWe are pleased to make this contribution in memory of Bob Back. Bob collaborated with our group at Chalk River on many projects over the last decade. He was a friend, colleague, and teacher to us and we have felt his absence on many occasions, not the least of which was while writing this article. We often asked one another, “How would Bob have explained the results?” Needless to say, Bob will continue to be missed. (1994)

McRae, G. A. ; Ivanco, M. ; Goodale, J. W.

New York, NY : Wiley-Blackwell

International Journal of Chemical Kinetics 26 (1994), S. 147-158

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ISSN: 0538-8066

Schlagwort(e): Chemistry ; Physical Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Multiphoton decomposition of 1-bromo 2-fluoroethane (CH2BrCH2F, BFE) with a two-color CO2 infrared laser is reported as a function of number of laser pulses. For single color irradiation at a wavelength chosen to excite BFE, the decomposition product, vinyl fluoride, which accumulates during the many-pulse MPD experiment, is found to deactivate BFE decomposition. When a second laser, tuned to a vinyl fluoride absorption is introduced, coincident with the first, the vinyl fluoride is found to activate further BFE decomposition. These results are accounted for in terms of a pressure-dependent model. Changes in model parameters, upon addition of the second laser, are shown to be consistent with interpretations in terms of collision-dependent reaction schemes. © 1994 John Wiley & Sons, Inc.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/kin.550260115

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Infrared multiphoton decomposition of highly excited t-butyl chloride-d9This article is dedicated to the memory of R.A. (Bob) Back, our mentor and friend. (1994)

McAlpine, Robertd ; McRae, Glenn A. ; Goodale, J. W.

New York, NY : Wiley-Blackwell

International Journal of Chemical Kinetics 26 (1994), S. 247-257

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ISSN: 0538-8066

Schlagwort(e): Chemistry ; Physical Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The infrared multiphoton decomposition (IR MPD) of t-butyl chloride-d9 as a function of pressure and fluence is reported. The major decomposition route was molecular elimination of DCl in accord with earlier pyrolysis studies. The effect of added gases (2-methyl propene-d8, DCl and 2-methyl propene-h8) on the MPD is presented. This study is a further example of the utility of a new method of analysis of MPD experiments. © 1994 John Wiley & Sons, Inc.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/kin.550260203

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