Spin-orbit splitting, .

Wliat is left to understand about this reaction One key remaining issue is the possible role of otiier electronic surfaces. The discussion so far has assumed that the entire reaction takes place on a single Bom-Oppenlieimer potential energy surface. Flowever, three potential energy surfaces result from the mteraction between an F atom and FI,. The spin-orbit splitting between the - 12 and Pi/2 states of a free F atom is 404 cm When... 

For high rotational levels, or for a moleeule like OFI, for whieh the spin-orbit splitting is small, even for low J, the pattern of rotational/fme-stnieture levels approaehes the Flund s ease (b) limit. In this situation, it is not meaningful to speak of the projeetion quantum number Rather, we first eonsider the rotational angular momentum N exelusive of the eleetron spin. This is then eoupled with the spin to yield levels with total angular momentum J = N + dand A - d. As before, there are two nearly degenerate pairs of levels assoeiated... 

Figure 4. Spin-orbit splitting in AT — 1 and 2 vibronic levels of the state of NCN. Solid lines connect the results of calculations thar employ ab initio computed potential curves [28], For comparison the results obtained by employing experimentally derived potential curves (dashed lines) [30,31] are also given. Full points represent energy differences between P — K — and P — K spin levels, and crosses are differences between P — K + I and P — K levels.

Spin-orbit splittings as well as binding energies of a particular electron level increase with increasing atomic number. The intensity ratio of the peaks from a spin-orbit doublet is determined by the multiplicity of the corresponding levels, equal to 2j + 1. Hence, the intensity ratio of the j = and j = components of the Rh 3d doublet is 6 4 or 3 2. Thus, photoelectron peaks from core levels come in pairs -doublets - except for s levels, which normally give a single peak. 

Levels with a non-zero value of the orbital angular momentum quantum number (1 > 0), i.e. p, d, f,... levels, show spin-orbit splitting. The magnitude of this splitting is too small to be evident in Figure 5.28, hence the double subscript for these levels (i.e. L2 3 represents both the L2 and L3 levels. 

The primary effects of relativity are contraction and energetic stabilization of the 6,v orbitals and expansion, destabilization, and spin-orbit splitting of the 5d orbitals, with consequences for the physical properties of the atoms and of the metals, and for bonding in their compounds these effects are strongest with Au, slightly weaker with Pt and Hg.56... 

U5 - 1 transitions within the spin-orbit split 3Tig (t g) ground state. Apart however from these observations no results are available. 

In the low energy region the measurements of Alien et al. went down only to 4 kK. but hexachlorobutadiene mull data indicated the presence of a further band at 3.0—3.4 kK.. This and the 5.6 kK. band were therefore readily identified as transitions within the spin-orbit split ground state manifold — the 3 kK. absorption as 3Tig (A) - 3i g (A) and the 5.6 kK. peak as 3Tlg (A) -+3T g (A, A). Allen et al. were unable to resolve the broad band at 30 kK. but it may be noted that six formally... 

In any future reexamination of the spectrum of the ReFg anion it may be anticipated that a moderately strong band should be found between ca. 5-10 kK., since the spin-orbit splitting of the zT g ground level again amounts to 3/2 f in the first order. 

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