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  • 1
    Electronic Resource
    Electronic Resource
    Reduction of the two-dimensional master equation to a Smoluchowsky type differential equation with application to CH4→CH3+H (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 8673-8679 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A master equation (ME) approximation describing the effect of vibrational/rotational (V/R) relaxation on unimolecular reactions in the gas phase is presented. It is demonstrated that some forms of ME can be transformed exactly to an effective two-dimensional Smoluchowsky type differential equation (SE) in the V/R energy variables, V and R. The SE allows interpretation in a unified way of both weak and strong collision limits. Analytical expressions for the unimolecular reaction rate coefficient ku(T) are derived for simple models of the energy dependence of the microscopic reaction rate k(V,R) and V/R density of states. For realistic k(V,R) (obtained from flexible transition state theory for the reaction CH4→ArCH3+H) the SE is solved numerically. Both numerical and analytical calculations show that the collisional rotational energy transfer can, in principle, affect the rate coefficient ku(T). However, for the particular reaction considered, ku is found to be less sensitive to changes in the average rotational energy transfer than to changes in the average vibrational energy transfer. Furthermore, the strong collision limit is achieved only for unrealistically large values of the average rotational energy transfer. This means that it is a good approximation in this case one can treat V/R energy transfer and dissociation by a one-dimensional master equation in total energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464474
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  • 2
    Electronic Resource
    Electronic Resource
    Potential energy function for CH3+CH3(arrow-right-and-left)C2H6: Attributes of the minimum energy path (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 7748-7761 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The region of the potential energy surface for the title reaction in the vicinity of its minimum energy path has been predicted from the analysis of ab initio electronic energy calculations. The ab initio procedure employs a 6–31G** basis set and a configuration interaction calculation which uses the orbitals obtained in a generalized valence bond calculation. Calculated equilibrium properties of ethane and of isolated methyl radical are compared to existing theoretical and experimental results. The reaction coordinate is represented by the carbon–carbon interatomic distance. The following attributes are reported as a function of this distance and fit to functional forms which smoothly interpolate between reactant and product values of each attribute: the minimum energy path potential, the minimum energy path geometry, normal mode frequencies for vibrational motion orthogonal to the reaction coordinate, a torsional potential, and a fundamental anharmonic frequency for local mode, out-of-plane CH3 bending (umbrella motion). The best representation is provided by a three-parameter modified Morse function for the minimum energy path potential and a two-parameter hyperbolic tangent switching function for all other attributes. A poorer but simpler representation, which may be satisfactory for selected applications, is provided by a standard Morse function and a one-parameter exponential switching function. Previous applications of the exponential switching function to estimate the reaction coordinate dependence of the frequencies and geometry of this system have assumed the same value of the range parameter α for each property and have taken α to be less than or equal to the "standard'' value of 1.0 A(ring)−1. Based on the present analysis this is incorrect: The α values depend on the property and range from ∼1.2 to ∼1.8 A(ring)−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465704
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  • 3
    Electronic Resource
    Electronic Resource
    Fitting of pressure-dependent kinetic rate data by master equation/inverse Laplace transform analysis (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 13452-13460 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100036a020
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetics of the unimolecular decomposition of isopropyl: weak collision effects in helium, argon, and nitrogen (1993)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 4450-4458 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100119a032
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  • 5
    Electronic Resource
    Electronic Resource
    Strong collision broadening factors from theories of unimolecular rate coefficients (1993)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 7556-7563 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100131a027
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  • 6
    Electronic Resource
    Electronic Resource
    Cathodoluminescence studies of sintered diamond (1985)
    Springer
    Journal of materials science 4 (1985), S. 681-684 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00726960
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  • 7
    Electronic Resource
    Electronic Resource
    Photoluminescence studies of sintered diamond compacts (1984)
    Springer
    Journal of materials science 19 (1984), S. 2405-2414 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Sintered diamond compacts have been examined by the technique of photoluminescence spectroscopy. The results suggest that the sintering process has produced considerable internal strain in the diamond grains, the amount of strain depending upon the grain size of the compacts; the smaller the grain size, the larger the amount of internal strain. Evidence is also presented for the formation of vacancies in the diamond grains during sintering, with the number of vacancies depending upon the grain size and the temperature of sintering. It is suggested that the vacancies are produced by the interaction of mobile dislocations during plastic deformation of the diamond grains when the compacts are being fabricated. A method is suggested for determining, under certain circumstances, the thermal gradients in a high pressure cell by examination of the luminescence spectra from diamond powders that have been compacted in different regions of the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01058119
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  • 8
    Electronic Resource
    Electronic Resource
    An investigation of plastic deformation in sintered diamond compacts using photoluminescence spectroscopy (1984)
    Springer
    Journal of materials science 3 (1984), S. 1090-1092 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00719773
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