1c:I[419806,["/_next/static/chunks/bb923814e1f4d2e9.js","/_next/static/chunks/dd3ee9f5b7716ca6.js","/_next/static/chunks/4204a0ae82542ca8.js","/_next/static/chunks/30036bedc5269936.js","/_next/static/chunks/6e1aa89a642f40be.js","/_next/static/chunks/cd5e572bc3e4eb92.js","/_next/static/chunks/8ffd0b71567920d8.js","/_next/static/chunks/67ea6dfd21f16c5f.js","/_next/static/chunks/24eb4379f68013fd.js","/_next/static/chunks/b8cd775ffdf935bd.js","/_next/static/chunks/983103cd9eb7b428.js","/_next/static/chunks/d4ac9dcf27f6ff52.js","/_next/static/chunks/294b9525248c8e5f.js"],"default"] 1d:T51b,The absorption and fluorescence of inorganic glasses and polycrystalline disks doped by heavy metal ions is discussed, and their use as fluorescence standards is evaluated. The advantages of the glass standards over other media is summarized. The glass standards are divided into two groups (1) glasses doped by trivalent rare earths such as Gd³⁺, Tb³⁺, Eu³⁺, Sm³⁺, and Tm³⁺ which have narrow band optical spectra as a result of intraconfigurational transitions, and (2) glasses and polycrystalline disks doped by ions such as Tl⁺, Pb²⁺, Ce³⁺, and Cu⁺ which have broad spectral bands since the optical spectra originate from interconfigurationally allowed transitions. Optical and physical parameters, including matrix effects, quantum efficiencies, decay characteristics, Stokes' shifts and spin-orbit versus orbit-lattice interactions due to the different transitions will be discussed. Group (1) glasses are suitable for use as standards where a narrow well-defined fluorescence range is required, and group (2) glasses are suitable for use as standards whenever a substance with a wide range of fluorescence is measured. Special emphasis will be placed on energy transfer between donor and acceptor ions.1e:T51a,The effects of pressure up to 50 kbar and of compositional changes on the absorption spectra of a number of chromium-containing silicate, phosphate, and borate glasses were observed. The spectra were analyzed into their component bands, and ligand-field theory was used to interpret the results to obtain information about the local symmetry, distortion, and local compressibility of the chromium sites. The absorption properties are explained by assuming that, on the average, the trivalent chromium ions are surrounded by six oxygen ions in an octahedral arrangement. The behavior of the spectra indicates that a random distribution of Cr–O distances about an average Cr–O distance exists and that only small disortions from cubic symmetry occur. The variation of the ligand-field parameters and the compressibilities of the sites depends mainly on the number of oxygen ions per unit volume in the glass, whether the changes are induced by external pressure or by compositional changes. Those glasses with a more open oxygen packing exhibit smaller crystal-field strengths, larger compressibilities, and larger distortions from octahedral symmetry than do the more densely packed glasses. Also, the compressibilities of the chromium sites are much less than the bulk compressibilities of the glasses.

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