Crystalline level schemes

Fig. 23. Energy level scheme of a single 3d electron showing the effect of crystalline fields (CF) of various symmetry. Electron occupation of levels is indicated by a circle in (d) and by arrows in (e) to denote spin polarization.

Fig. 13. Kissinger-Boswell plot of the crystallization temperature in amorphous Dyo o °o.40 studied as a function of the heating rate i (bottom and right-hand scales). The level scheme on the left-hand side indicates the relative energies of the crystalline state (c), the amorphous state (a), and the transitional or activated state (t).

Fig. 17.29, Excitation spectrum of in a cubic crystalline field with nearest neighbour interactions. The CEF level scheme is shown in fig. 17.30, q is in (111) direction and T = 1.21 (from Peschel et al., 1972).

PrPtBi Measurements were initially made on powder samples prepared by arc melting (Suzuki et al., 1997). The electrical resistivity ( 1 mf2cm at 300 K) and Hall coefficient ( 0.7 cm /C at low temperatures) are consistent with semiconductivity. The magnetic susceptibility follows the Curie-Weiss law above 50 K but tends to become temperature-independent below 50 K. The specific heat curve shows a prominent anomaly at 1.35 K. A crystalline electric field (CEF) level scheme was derived from inelastic neutron scattering... 

Treatment of intermediate 31 with 2.2 equiv of 4-FB A in EtOH at 72 °C afforded 35 as a white crystalline solid in 90% isolated yield (Scheme 6.9). Hydrogenation in the presence of 5% of Pd/C and 1 equiv of MsOH, efficiently removed the Cbz-protected group. MsOH was used to prevent fluoride reduction resulting in low levels of the des-fluoro by-product. Catalyst filtration, followed by neutralization of the crude reaction mixture with NaOH, afforded free amine 36 as a white crystalline product in 99% isolated yield. Free-amine 36 was isolated as a dihydrate which necessitated drying prior to coupling with oxadiazole chloride 2. 

Scheme 9.28). Despite the modest enantioselectivity, we knew from our previous work that upgrade of enantiomeric purity was possible via preferential removal of the less soluble racemic material by crystallization. In this manner, after a carbon treatment to achieve acceptable levels of residual rhodium, racemic 1 was removed by partial crystallization, followed by subsequent isolation of 1 as a crystalline solid in 72% yield from 22, and in 98.5% ee. 

Most published work on the energy levels in the trivalent lanthanides and actinides has been carried out in crystalline media, where the identity of a level in terms of a given coupling scheme can be experimentally established 8, 19). In attempting similar correlations in aqueous solution, one must rely heavily on the level identifications established in crystals. Where crystal data is not available, extrapolation of parameters... 

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