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961.
962.
Hydrogen-bonded banana liquid crystals 总被引:1,自引:0,他引:1
Gimeno N Ros MB Serrano JL de la Fuente MR 《Angewandte Chemie (International ed. in English)》2004,43(39):5235-5238
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The intermolecular vibrational energy transfer from triplet molecules of benzophenone and anthraquinone to H2O molecules has been investigated. To determine the rates of establishment of vibrational (V-V) and thermal (V-T) equilibrium in a vibrational quasi-continuum of mixed singlet-triplet levels, the dependences of the decay rates and intensities of the fast and slow components of delayed fluorescence on the H2O vapor pressure have been investigated. For V-V relaxation, the efficiencies 1 and the mean energies E transferred per collision in mixtures with H2O and other polyatomic foreign gases have been compared. It has been established that the efficiencies 1 for quasi-resonant vibrational energy transfer (V-V) from benzophenone and anthraquinone to H2O are an order of magnitude lower than the gas-kinetic ones and lower than those obtained under the same experimental conditions for such foreign gases as C5H12, SF6, and CCl4, and decrease with increasing temperature in the 433–513 K range. It has been concluded that the mechanism of V-V relaxation in mixtures with H2O are determined by long-range attractive forces. In mixtures with H2O, no acceleration of V-T relaxation due to the formation of hydrogen bonds has been revealed. The low-efficiency thermalization process (V-T relaxation) is controlled by short-range repulsive forces, and the differences between the intensities 2 for mixtures of benzophenone and anthraquinone with H2O and other polyatomic gases are determined by the change in the reduced mass of interacting molecules. 相似文献
970.
G Budak 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,88(4):525-532
The X-ray absorption jump factor and jump ratio of Gd, Dy, Ho and Er were measured with a Si(Li) detector by attenuation, with Gd, Dy, Ho and Er foil, a Compton peak produced by the scattering of the Am-241 Gamma rays. Al was chosen as secondary exciter. The experimental absorption jump factors and jump ratios are compared with the theoretical estimates of WinXcom (Radiat. Phys. Chem. 60 (2001) 23), McMaster (Compilation of X-ray cross sections UCRL-50174, 1969; Sec. II. Rev. I), Broll (X-ray Spectrom 15 (1986) 271), Hubbel and Seltzer (NISTIR (1995) 5632) and Budak (Radiat. Meas. accepted for publication). The present results constitute the first measurement for this combination of energy and elements, and good agreement is obtained between experiment and theory. 相似文献