Rovibrational states/levels

Fig. 27. Comparisons of the rovibrational state distributions obtained from the 0(1D) reaction with H2 at the j = 0 and j = 1 levels at the backward scattering 117° LAB angle.

A particular effort has been addressed to the study of the dynamics within the dimer and to the characterization of fhe low lying rovibrational states in view of pofenfial inferesf for fhe analysis of spectral features in atmospheric research. Calculations of fhe bound rovibrational states of the dimers have been performed for rofafional sfafes having fofal angular momentum / < 6 by solving the secular problem over the exact Hamiltonian. We have calculated the rovibrational levels for the potential energy surfaces described above of the dimers N2-N2, N2-O2 and for all fhree surfaces (singlet, triplet and quintet) [4,5] of O2-O2. A summary of resulfs and fheir discussion follows. Full accounf of all available data has been given in [5,6,8-10]. 

The quantitative description of ultracold molecule-molecule collisions is another challenging topic. The recent progress on the H2-H2 system will be difficult to implement for heavier systems due to the large number of rovibrational levels of the molecules. The study of H2-H2 collisions has shown that, for certain combinations of rovibrational levels, the energy transfer may occur to specific final rovibrational states. In such cases, the calculations can use a much smaller basis set without compromising the accuracy. 

A number of corrections need to be made to the ion image intensity during analysis of these images. A correction for solid angle, nuclear indistinguishability (the even (para) J levels are multiplied by three [23,54]) and detection sensitivity were all applied to the data. The procedure described by Kliner et al. [24,53,55-57] to correct measured signal intensities to allow for differences in ionization efficiency between the various rovibrational states of H2 arising from the (2+1) REMPI detection scheme was also applied. 

Figure 4.29 RKR points for the Ig state of NSg. These are the classical turning points R-, R+ calculated for v" = 0 through 45 using spectroscopically determined rovibrational energy levels from Na2 fluorescence spectra. Separations are given in A. Data are taken from P. Kusch and M. M. Hessel, J. Chem. Rhys. 68 2591 (1978).

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. 

Radiometry. Radiometry is the measurement of radiant electromagnetic energy (17,18,134), considered herein to be the direct detection and spectroscopic analysis of ambient thermal emission, as distinguished from techniques in which the sample is actively probed. At any temperature above absolute zero, some molecules are in thermally populated excited levels, and transitions from these to the ground state radiate energy at characteristic frequencies. Erom Wien s displacement law, T = 2898 //m-K, the emission maximum at 300 K is near 10 fim in the mid-ir. This radiation occurs at just the energies of molecular rovibrational transitions, so thermal emission carries much the same information as an ir absorption spectmm. Detection of the emissions of remote thermal sources is the ultimate passive and noninvasive technique, requiring not even an optical probe of the sampled volume. 

---