Fine structure components

Further information on this system is available from studies directed at photochemical isotope enrichment (16). In this work a mercury resonance lamp containing only Hg19S was used as a source. A flowing mixture of natural mercury and water vapor exposed to the Hg198 fine structure component of the mercury resonance radiation (2537 A.) was found to result in HgO considerably enriched in Hg198. It was concluded that this could only occur if Hg(3Pj) atoms reacted in a primary step to form either a compound which is removed from further contact with the reaction or which itself may react further but must not regenerate free Hg. Either reaction (55) or (56) would satisfy these conditions. If reaction (55) is the primary reaction, the further reaction... 

If in these expressions one neglects the differences in the fine-structure components... 

Reactions within a van der Waals (vdW) complex of calcium with hydrogen halides (HC1 and HBr) lead to electronically excited calcium halides. These reactions have been quite extensively studied in full collisions of excited calcium beams (Brinckmann et al. 1980 Brinckmann and Telle 1977 Rettner and Zare 1981, 1982 Telle and Brinckmann 1990). The electronic excitation of the calcium atom results in a strong chemiluminescence under collisional conditions. The efficiency of this chemiluminescence depends upon the electronic state and the fine structure component, and the final product state is influenced by the preparation conditions of the collision. In the reaction Ca(4s4p1P1) + HC1, the direction of the polarization of the P orbital with respect to the collision relative velocity (pK or pff) has an effect on the branching ratio to the products CaCl, A2n or B2X+ (Rettner and Zare 1981, 1982). 

Same fit as that of Fig.5a) for the two fine structure components of the 2S-20D transition... 

Fig. 1 shows an early saturation spectrum of the hydrogen Balmer-a line, recorded in this way at Stanford [4], together with the seven theoretically predicted fine structure components and the Doppler-... 

The spin-orbit coupling therefore removes the degeneracy of the so-called fine-structure states listed above. For example, simply by substituting the appropriate values of J, L and S, the three fine-structure components arising from the L = 1, S= 1 configuration are calculated to have the following first-order spin orbit energies ... 

For NO the 2n 1/2 fine structure component lies lower than the 2n3/2 this is called a regular 2U state. Each level in figure 6.18 is actually doubly-degenerate, because of the /t-doubling, which is indeed resolved in the rotational spectrum of NO. The transition from case (a) to case (b) coupling, which is also called spin-decoupling,... 

The lowest fine structure component is the 2n3/2 state, and the lower rotational levels for both OH and OD are shown schematically in figure 8.44. Each rotational level is split into a /t-doublet, indicated in figure 8.44, but not at all to scale. Moreover, each A-doublet level in OH is further split into a doublet by magnetic hyperfine interaction with the proton. This is illustrated in figure 8.45 for the lowest rotational level, J = 3/2, and the observed electric dipole transitions are also shown each rotational level possesses a similar A-doublet and hyperfine structure. 

Historically the first open shell molecule to be studied by magnetic resonance methods was nitric oxide, NO. The 2n1/2 fine-structure component is lower in energy than the 2n3/2 component by 123 cm 1 and is only weakly magnetic. However, the 2n3/2 component is substantially populated at room temperature and its microwave magnetic resonance spectrum is readily recorded. Spectra of the lowest rotational level,... 

Before examining the effect of an applied magnetic field it is instructive and hopefully helpful to look at the matrix of the above five terms. For each of the three fine-structure components with a given J value there are two parity states, labelled e and /. According to the now accepted convention [68] for integral J values, levels with parity - -(—l) 7 are called e levels and levels with parity —(— If 7 are called / levels. The matrix is as follows. 

We now look at the matrix elements, in e and / pairs for each fine-structure component. 

Figure 9.39. Fine-structure components, rotational levels, and observed rotational transitions for Cold in its v = 0 X 34 and 33 fine-structure components. The remaining = 2 spin component lies at about 1500 cnT1 above the lowest one.

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