Electronic transitions, lanthanide laser ions

Table II. Electronic transitions and and actinide lasers. ions used for lanthanide...

The rare earth (RE) ions most commonly used for applications as phosphors, lasers, and amplifiers are the so-called lanthanide ions. Lanthanide ions are formed by ionization of a nnmber of atoms located in periodic table after lanthanum from the cerium atom (atomic number 58), which has an onter electronic configuration 5s 5p 5d 4f 6s, to the ytterbium atom (atomic number 70), with an outer electronic configuration 5s 5p 4f " 6s. These atoms are nsnally incorporated in crystals as divalent or trivalent cations. In trivalent ions 5d, 6s, and some 4f electrons are removed and so (RE) + ions deal with transitions between electronic energy sublevels of the 4f" electroiuc configuration. Divalent lanthanide ions contain one more f electron (for instance, the Eu + ion has the same electronic configuration as the Gd + ion, the next element in the periodic table) but, at variance with trivalent ions, they tand use to show f d interconfigurational optical transitions. This aspect leads to quite different spectroscopic properties between divalent and trivalent ions, and so we will discuss them separately. 

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... 

Gas Phase Experiments. - In gas phase laser ablation experiments with organic ligands, novel organometallic network structures were obtained. With 3d transition metals and benzene, two kinds of structures, multiple sandwich and rice-bair, were formed, depending on the nature of the metal. The multiple-decker sandwich structures were also formed with lanthanide atoms and COT. Not surprisingly, such clusters consist of positively charged Ln ions and COT dianions. Their electronic structure is fairly ionic and is localized around each metal atom. ... 

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