Rovibrational manifold

One can also see from the relative heights of the density and order parameter components in Figures 2.3a and 2.3b that the overall response of the nematic film is different for the two forms of excitatioa The absorption of infrared photons (A, = 10.6 pm) corresponds to the excitation of the ground (electronic) state s rovibrational manifold, whereas the visible photoabsorption (k = 0.53 pm) corresponds to the excitation of the molecules to the electronically excited states (see Fig. 2.5). The electronic molecular stractures of these two excited states are different and may therefore account for the different dynamical response behavior of the order parameter, which is dependent on the intermolecular Coulombic dipole-dipole interaction. From this observation one may conclude that the dynamical grating technique would be an interesting technique for probing the different dynamical... 

These values were, in turn, averaged over the manifold of rovibrational wavefunctions belonging to the vibrational ground state. Finally, a mean value was found on the assumption that there is a Maxwell-Boltzmann distribution of molecules in the rotational levels (for this the temperature 295K was assumed). 

We also failed to detect by LIF any electronically excited A10(A Ili) product, by excitation on B-A transitions in the fundamental range of rhodamine dyes, and collecting the fluorescence of B-X transitions. Combined factors are certainly responsible for the low LIF signals the spread of the products on the large manifold of accessible rovibrational states, the high recoil velocities which lower the densities, and perhaps a lower reactive cross-section than for the other reactions. 

Diatomic Molecules Hg, Dg, Ng, Og, CO, NO. The following table gives the rate constants and cross sections generally measured at room temperature (except those falling under remarks e) to h)). These are either for a selected rovibrational level v = 0, N, J of the A Ilj state (mostly the lowest one) or for a manifold of N, J levels which may exhibit the normal (Boltzmann) distribution or some other hot distribution. Explanations, some other details, and additional results are given in the remarks following the table. Results for ND are given in braces. 

Explicit expressions for the prior distributions require the expressions for the energies of the rovibrational states. For most diatomics, it is sufficient to use the rigid rotor approximation Eyj = E + Byj(j + 1), where By is the rotational constant in the vibrational manifold v. It is however necessary to recognize the anharmonicity of the vibrational levels because near the energy cutoff, the ttans-lational density of states oc(E - E v, ) varies quite rapidly. 

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