Absorption separation from lanthanides

Multiphoton absorption induced emission from lanthanides emitting in the visible region is by far most studied with Eu and Tb, which are the most widely used metals as they have favorable emission windows and larger separations of... 

An attractive feature of the Judd-Ofelt approach is that once the intensity parameters are determined, they can be used to calculate the probability of transitions between any 4f" levels of interest for laser action. This includes absorption and fluorescence intensities, excited-state absorption, radiative lifetimes and branching ratios, and, combined with fluorescence spectra, stimulated emission cross sections (Krupke, 1974a). Best results are obtained for the lower-lying levels of 4f" which are well separated from the opposite-parity configurations and thus in keeping with the approximations made by Judd and Ofelt. Since the Judd-Ofelt parameters are not expected to differ greatly for adjacent ions in the lanthanide series, estimates can be made using extrapolated n values. 

The basis for the claim of discovery of an element has varied over the centuries. The method of discovery of the chemical elements in the late eightenth and the early nineteenth centuries used the properties of the new sustances, their separability, the colors of their compounds, the shapes of their crystals and their reactivity to determine the existence of new elements. In those early days, atomic weight values were not available, and there was no spectral analysis that would later be supplied by arc, spark, absorption, phosphorescent or x-ray spectra. Also in those days, there were many claims, e.g., the discovery of certain rare earth elements of the lanthanide series, which involved the discovery of a mineral ore, from which an element was later extracted. The honor of discovery has often been accorded not to the person who first isolated the element but to the person who discovered the original mineral itself, even when the ore was impure and that ore actually contained many elements. The reason for this is that in the case of these rare earth elements, the earth now refers to oxides of a metal not to the metal itself This fact was not realized at the time of their discovery, until the English chemist Humphry Davy showed that earths were compounds of oxygen and metals in 1808. 

The separation of yttrium from the lanthanides is performed by selective oxidation, reduction, fractionated crystallization, or precipitation, ion-exchange and liquid-liquid extraction. Methods for determination include arc spectrography, flame photometry and atomic absorption spectrometry with the nitrous oxide acetylene flame. The latter method improved the detection limits of yttrium in the air, rocks and other components of the natural environment (Deuber and Heim 1991 Welz and Sperling 1999).Other analytical methods useful for sensitive monitoring of trace amounts of yttrium are X-ray emission spectroscopy, mass spectrometry and neutron activation analysis (NAA) the latter method utilizes the large thermal neutron cross-section of yttrium. For high-sensitivity analysis of yttrium, inductively coupled plasma atomic emission spectroscopy (ICP-AES) is especially recommended for solid samples, and inductively coupled plasma mass spectroscopy (ICP-MS) for liquid samples (Reiman and Caritat 1998). 

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