Vibrational energy disposal

Ex 35 Kcal/mole.15 We find that the CO product vibrational distribution calculated using the phase space model with Eav = 35-40 Kcal/mole is in good agreement with our experimental results (Figure 2). Thus, the measured CO vibrational distribution indicates that vibrational energy disposal to the photolysis products is determined at a point on the potential surface where the full reaction exoergicity is available. This suggests that the 351 nm excitation of W(CO)g results in the sequence of events, (2)-(4), where the asterisk denotes vibrational excitation. 

Time-resolved CO laser resonance absorption used to 518 study vibrational energy disposal pattern in CO following photofragmentation of 3-cyclopentenone 220—270 nm photolysis of succinic anhydride shown to 519 produce COj, CO, and CjH but not in quantities... 

This result conflicts with a theoretical calculation of the vibrational energy disposal which while reproducing the s >- S " absorption profile, predicts very little excitation of N2 W >0 unless the parent N2O is vibrationally excited. 

Dynamic Models for Vibrational Energy DisposaL —Busch and Wilson identified... 

Equation (39) is a more realistic expression of the ultra-simple, one-dimensional Golden Rule formula. -It expresses the importance of structural changes in dictating the vibrational energy disposal in the photofragments but... 

As a general summary of the present situation, it is evident that attempts to model observations of the vibrational energy disposal in photodissodation, while often successful, have also been equivocal. There is a consensus on the major influence of structural changes expressed in terms of Frandt-Condon considerations, and the basic framework of a rigorous, quantum mechanical treatment has been constructed, but comparison with experimental data does not seem to be a very discriminating test in general. 

The good agreement between experiments and quantum scattering calculations demonstrates that modem quantum reactive scattering calculations, which in the past were verihed only for three-atom systems in three dimensions, are now able to predict vibrational energy disposal in four-atom reactions, which involve six dimensions (see Pogrebnya et al. (2000)). 

The surprisal plots tend to be linear for all three prior distributions unless dynamical restrictions are present. Then surprisal plots for I and II become nonlinear. Extrapolation of the surprisal plots to = 0 facilitates assignment of the relative v=0 population. The vibrational energy disposal for the CHjX(X = F, Cl, Br, I) series are all characterized by the same X . 

The pairwise members of the series (CH, - HCl), (SiH, -HBr), GeH - HI) have very similar vibrational energy disposal as measured by and Xy using model I as the... 

These conclusions show that three-body behavior dominates the vibrational energy disposal of the CH X systems, as well as SiH, and GeH. The y values found for the above reactions are model I, (4.7 + 0.7) model II (10 + 1) and model III (15 + 1). Thus, with the aid of surprisal analysis, the product vibrational distributions for all of the above systems can be compactly expressed, within the experimental error, by the parameters X and Xy. The fact that the same vibrational disequilibrium is o%-tained in the above cases confirms, via information theory, that all reactions follow similar dynamics. 

The evidence presented in Tables 2 and 3 for the reaction of 0( D) with H2 via insertion indicates that the loose collision complex survives about one rotational period (about 0.2 ps) and that the tight complex lives about 0.03 ps. Visual inspection of several trajectories in computer-animated movies showed that the complex vibrates several times before it decays into products. Thus, there may be sufficient time for the available energy to be partitioned equally among the various vibrational modes of the complex, so that the vibrational energy disposal would be governed by statistics. 

The vibrational energy disposal has been studied by the infrared chemiluminescence technique for a large number of polyatomic molecules (see Table 2.6) however, the interpretations are not as advanced as for the F + HR systems. The rotational energy disposal is somewhat less completely studied, but such data can be expected in the near future. With certain exceptions, the energy disposal generally resembles that of the H + Xa reactions with small , moderate , and nonlinear vibrational surprisals and failure of the HCl or KF product distribution to extend to the thcriiiO-chemical limit. The reactions with NOCl and the sulfur chlorides have been studied in greatest detail and the discussion will be focused on these reactions. 

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