Trivalent energy-level schemes

The energy levels scheme of trivalent REE may be seen in Eig. 5.1 and excitation... 

Fig. 5.1. Energy levels scheme of trivalent rare-earth elements...

An examination of the trivalent actinide energy level schemes reveals several possibilities for laser action. These are discussed in light of the general properties cited above. Only conventional broadband optical pump sources are considered. Obviously with selective laser excitation and cascade lasing schemes, stimulated emission from many more states should be possible, but these special situations are too numerous to be considered in detail here. 

Fig. 4.13 Energy-level scheme of divalent and trivalent lanthanides in Cap2. Energies corresponding to Ln and Ln " are indicated by blue dashed lines and red solid lines, respectively. The lowest states of 4f electronic configurations are re nesented by triangles. Possible 4f 5d — 4f transitions are indicated by vertical arrows. Reprinted from Ref. [153], copyright 2004, with permission fiom Elsevier...

Values of the quantity P > 0.015 x 10" where Pmd= P n have been calculated for all of the trivalent lanthanide ions based on eigenvectors derived from energy level schemes for R (aquo) (Carnall et al., 1968a). The principal magnetic dipole transitions in the absorption spectra of the 3+ lanthanides are identified in table 24.3. 

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... 

The field of lathanide lasers is mature but not exhausted. Additional laser schemes and materials will undoubtedly be exploited. There are 1639 free-ion energy levels associated with the 4fn electronic configurations of the thirteen trivalent lanthanides. Yet, of the 192,177 possible transitions between pairs of levels, by mid-1979 only 41 had been used for lasers. It is certain that given suitable pump sources and materials, stimulated emission involving many... 

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