Implications of Berthlot`s descriptive of associative reactions

Berthelot`s equation, k{sub {infinity}}(T) = A{sub {infinity}} exp (-Dk{sub B}T), provides a good description of the high-pressure rate coefficient for associative reactions such as CH{sub 3} + CH{sub 3}, CH{sub 3} + OH, and CH{sub 3} + H. The parameter D may be used to characterize an effective temperature-dependent barrier, {Delta}E{sub eff} = Dk{sub B}{sup 2}T{sup 2}, which is due to the internal energy, i.e. rotational and vibrational energy, or the centrifugal barrier of the associating species. The parameter A{sub {infinity}} may be identified as the rate coefficient for association when the species approach one another with zero translational and internal energy. A microcanonical rate expression is given which may be used to directly compare experimental results with theoretical calculations. In addition, this approach suggests that the Arrhenius expression for the high-pressure rate coefficient for dissociation should contain both the change of enthalpy of the reaction and this effective barrier

Elementary reaction rate measurements at high temperatures by tunable-laser flash-absorption

The major objective of this program is to measure thermal rate coefficients and branching ratios of elementary reactions. To perform these measurements, we have constructed an ultrahigh-purity shock tube to generate temperatures between 1000 and 5500 K. The tunable-laser flash-absorption technique is used to measure the rate of change of the concentration of species which absorb below 50,000 cm{sup {minus}1} e.g.: OH, CH, and CH{sub 3}. This technique is being extended into the vacuum-ultraviolet spectral region where we can measure atomic species e.g.: H, D, C, O, and N; and diatomic species e.g.: O{sub 2}, CO, and OH

Fluorescence and excitation spectra of Bk/sup 3 +/, Cf/sup 3 +/, and Es/sup 3 +/ ions in single crystals of LaCl/sub 3/

Self-fluorescence measurements have two disadvantages: the excitation and relaxation mechanisms are not understood, therefore the fluorescing level is difficult to assign, and fluorescence from daughter ions is also present. To obtain the 5f/sup n/ ion energy level structure with the highest possible precision, ions dilutely substituted into single crystal host lattices are needed. Concentrated systems such as EsBr/sub 3/ will exhibit line broadening due to ion-ion interactions. This limits the usefulness of any pure system. The use of dye laser techniques to study the energy level structure of the heavier actinides in single crystals of LaCl/sub 3/ is discussed. (GHT