Cerium In

Several instmmental methods are available for quantitative estimation of from moderate to trace amounts of cerium in other materials. X-ray fluorescence is widely available, versatile, and suitable for deterrninations of Ce, and any other Ln, at percent levels and lower in minerals and purer materials. The uv-excited visible luminescence of cerium is characteristic and can be used to estimate Ce content, at ppm levels, in a nonluminescing host. X-ray excited optical luminescence (15), a technique especially appropriate for Ln elements including cerium, rehes on emissions in the visible, and also measures ppm values. Atomic emission spectrometry is appHcable to most lanthanides, including Ce (16). The precise lines used for quantitative measurement must be chosen with care, but once set-up the technique is suitable for routine analyses. 

The role of cerium in these lighting phosphors is not as the emitting atom but rather as the sensitizer. The initial step in the lighting process is the efficient absorption of the 254 nm emission Ce ", with broad absorption bands in the uv, is very suitable. This absorbed energy is then transferred to the sublattice within the crystalline phosphor eventually the activator ion is fed and emission results. Cerium, as a sensitizer ion, is compatible in crystal lattices with other lanthanide ions, such as Eu and Tb, the usual activator atoms. 

Cerium is one of the most widely used activators, which improve the working characteristics of many scintillators. Determination of the valence state of cerium in single crystals of alkaline and rare-earth borates allows to establish the nature of activator centers for purposeful influence on the scintillation efficiency of the matrix. 

To develop a better understanding of the potential health consequences of radiocerium in our environment, it is important to know the possible sources and physical and chemical forms of its release. The metabolism and dosimetry of internally-deposited radiocerium are highly dependent upon the forms of the material presented to the body and the mode of exposure as discussed in Section 3—Metabolism of Cerium in Mammalian Species. 

Table 10—Gastrointestinal absorption of cerium in laboratory animals ...

Fig. 2b. Bone and liver uptake of inhaled cerium in Class D, W and Y compounds (no radioactive decay) as projected from the TGLD model coupled with the ICRP committee II model for radiocerium,...

Hirano, S., Koyanagi, T. and Saiki, M. (1973). The physico-chemical behaviour of radioactive cerium in seawater, page 47 in Radioactive Contamination of the Marine Environment, IAEA Publication No. STI/PUB/313 (International Atomic Energy Agency, Vienna). 

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