Other Transitions

The spectrum of Mn2+ in zeolites has been used to study the bonding and cation sites in these crystalline materials. This is a 3d5 ion hence, one would expect a zero-field splitting effect. A detailed analysis of this system was carried out by Nicula et al. (170). When the symmetry of the environment is less than cubic, the resonance field for transitions other than those between the + and — electron spin states varies rapidly with orientation, and that portion of the spectrum is spread over several hundred gauss. The energies of the levels are given by the equation... 

To obtain reference points at lower temperatures, as we shall see (Sections 8.4, 8.5), transitions other than (a)-(e) are necessary. 

As illustrated in Fig. 41 (see p. 84), the number of observed Cu-ENDOR lines (63Cu enriched sample217 ) does not follow the usual ENDOR selection rules for EPR observers with resolved hfs (two transitions for EPR observers with mi = I, four transitions for EPR observers with - I < n < I Sect. 3.2). This may be due to transfer of microwave saturation to EPR transitions other than the one which is used as an observer. A corresponding effect has been observed in Co-ENDOR spectra of Co(acacen)61. ... 

Thus the present model is able to express thermoshrinking type of transition. Other calculated results with the variation of the parameter values indicated that the model could be applied to the convexo-type of transition. 

Certain semi-empirical methods are aimed at choosing the effective potential, allowing one to determine as accurately as possible values of oscillator strengths of electronic transitions others, more complex, are also directed at achieving the best correspondence between calculated energy spectra and experimental ones. 

There were lines in the spectra corresponding to transitions other than simply between two n values (cf. Eq. 4.14). This was rationalized by Sommerfeld in 1915, by the hypothesis of elliptical rather than circular orbits, which essentially introduced a new quantum number k, a measure of the eccentricity of the elliptical orbit. Electrons could have the same n but different k s, increasing the variety of possible electronic transitions k is related to what we now call the azimuthal quantum number, Z l = k — 1). 

These transitions have been called inter-ligand transmetallic charge transfer transitions. Other types of transitions are present in polynuclear transition metal complexes6 7- but we will not deal with such compounds. 

When the interaction frequency Larmor precision frequency, col, the resonance transitions other than the principal one, Vi —Vi are generally difficult to observe. In such a situation the value of e2qQ is obtained from the splitting of the principal transition. The values of e2qQ obtained as a function of temperature are plotted in Fig. 2.7. 

Table 2.3 Types of metal-centered transitions other than d-d. ...

The existing experimental data ( 4, 1 ) did not indicate any transitions other than a crystal-liquid transition. Lacking... 

Figure 3. Spontaneous strains and elastic properties at the 422 < i> 222 transition in Te02. (a) Spontaneous strain data extracted from the lattice-parameter data of Worlton and Beyerlein (1975). The linear pressure dependence of (e - (filled circles) is consistent with second-order character for the transition. Other data are for non-symmetiy-breaking strains (e + 62) (open circles), 63 (crosses), (b) Variation of the symmetry-adapted elastic constant (Cn - Cu) at room temperature (after Peercy et al. 1975). The ratio of slopes above and below Po is 3 1 and deviates from 2 1 due to the contribution of the non-symmetry-breaking strains. (After Carpenter and Salje 1998).

---