Vibrational heating

Wen X, Tolbert W A and DIott D D 1993 Ultrafast temperature ]ump in polymers phonons and vibrations heat up at different rates J. Chem. Phys. 99 4140-51... 

The vibrational heat capacity is the largest contribution to the total heat capacity and determines to a large extent the entropy. Analytical expressions for the entropy of the models described in the previous section can be derived. The entropy corresponding to the Einstein heat capacity is... 

E. Torrontegui, S. Ibanez, X. Chen, A. Ruschhaupt, D. GuuLery-Odelin, and J. G. Muga. Fast atomic transport without vibrational heating. Phys. Rev. A, 83(1) 013415-013423(2011). 

III. Vibrational Heating Using Nondestructive Optical Cycling... 

Alternatively, when process (3) is slower than (4) or (5), but faster than (1) or (2), A will again relax by the route (3) followed by (4) or (5), but now (3) will be rate determining. This will give a linear variation of 1// A with x. B will relax independently, and more rapidly, via (4) and (3), with linear dependence of 1// B on x. There will thus be a double relaxation phenomenon with two relaxation times, PA involving only the vibrational heat capacity of A, and / B only that of B, both showing linear concentration dependence. This mechanism is analogous to the relaxation behaviour discussed in Section 3.1 for pure polyatomic gases, which show double dispersion because vibration-vibration transfer between modes is slower than vibration-translation transfer from the lowest mode. 

In Fig. 5, additionally the calculated and measured vibrational temperatures [50] are plotted. In contrast to the rotational cooling, there is vibrational heating indicating that there should be enhanced dissociation for vibrating hydrogen molecules on Pd(l 00). Vibrationally enhanced dissociation has been known for years in the gas phase dynamics community [53]. Usually it is associated with strongly curved reaction paths in activated systems [4]. However, the most favorable path towards dissociative adsorption in the system H2/Pd(l 0 0) is purely attractive and has a rather small curvature (see Fig. 2a). Therefore one would not expect any substantial influence of the vibrational state of H2 on the sticking probability. 

Several attempts have been made to make s more than just a fitting parameter without losing the simplicity of the model. For example Benson suggested that the number of effective oscillators s could be estimated from the molar vibrational heat capacity, s = [15], and Troe has similarly used the energy,... 

The vibrational heating efficiency of LiH molecules in collisions with He atoms was the subject of further study [34], The excitation and relaxation rates over a broad range of temperatures were reported, together with the average energy transfer indices. It was found that in spite of the weak nature of the van der Waals interaction, the strong anisotropy of the surface leads to rovibrational excitation rates which are larger, for example, than those exhibited by the He-CO [35] or He-N2 [36] systems. 

Hot-electron-induced vibrational heating at surface - importance of a quantum-mechanical description. Surf. Sci., 341, L1031-L1036. 

Properly designed fuel cells may be as much as 70 percent efficient, about twice as efficient as an internal combustion engine. In addition, fuel-cell generators are free of the noise, vibration, heat transfer, thermal pollution, and other problems normally associated with conventional power plants. Nevertheless, fuel cells are not yet in widespread use. A major problem lies in the lack of cheap electrocatalysts able to function efficiently for long periods of time without contamination. The most successful application of fnel cells to date has been in space vehicles (Figure 19.12). 

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