Effective energy gap

The rock salt nitrides are formed only if there are three or less d electrons on the formally ionic cation, so that the e orbitals are empty and the t2g orbitals are half or less filled. In a simple ionic model, there is an effective energy gap due to an overlapping of the energy... 

Redistribution of the space-charge of the excited carriers is presented in Fig. 1. Therewith at low temperatures, as seen in Fig. 2, the tunable photoluminescence band maximum coincides with the difference of the quasi-Fermi levels AF, which in turn is close to the effective energy gap Eg of the doped superlattice. At... 

Figure 2. Dependence of the effective energy gap Eg on the quasi-Fermi level difference AF in the superlattice No. 4 at 20 K (a) and 300 K (b). Thin curves represent the quasi-Fermi level for electrons Fe relative to the top of the valence band, dashed curves correspond to the quantum energy of the spontaneous recombination spectrum maximum hvmax.

The measurement and analysis of the magnetic susceptibihly can give further independent information on the electronic stracture of the (Fa)2Pp6 crystals. In particular, from the temperature dependence of the susceptibility, the effective energy gap 2 Aeff above the Peierls-transition temperature Tp can be directly derived. 

Mfn = 549.5 g/mol (Fa)2PF6.) Solid curves calculated temperature dependence for thermally-activated paramagnetism (t.a.p.) and for the paramagnetism of the conduction electrons with an effective energy gap of 2Aeff(T) in the quasi-metallic state for T> Tp, according to the Lee-Rice-Anderson model (L-R-A). From [29]. 

Fig. 9.20 The temperature dependence of half the effective energy gap, Aeff(T), of the (Fa)2PF6 crystal, computed from the temperature dependencies of the static magnetic susceptibility and the ESR intensity (ESR of the conduction electrons. From [29].

The qualitative features of the Knight shift behavior in liquid mercury are suggestive of the opening of an effective energy gap of the Bloch-Wilson type (Sec. 2.3.3a) even though it is likely that the specific density at the trancition is affected by electron correlation effects (Bhatt... 

In writing Equation 3.75, we have included the single-mode generating function Gj(t) from (3.72) into Gw(t). The former is reduced in the approximation used above to Gj(t) = (1—exp(—RcOri/feBT)) and its contribution to Gn(4) is approximately unity. From Equation 3.75, we deduce that the effect of the promoting mode is to decrease or increase the effective energy gap to h Q =p Mt )- For transitions that terminate in the first vibrational excited level n, = 1 of the I electronic state, the... 

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