Nuclear energy spectroscopy

MS Mossbauer Spectroscopy [233-236] Chemical shift of nuclear energy states, usually of iron Chemical state of atoms... 

The detection and determination of traces of cobalt is of concern in such diverse areas as soflds, plants, fertilizers (qv), stainless and other steels for nuclear energy equipment (see Steel), high purity fissile materials (U, Th), refractory metals (Ta, Nb, Mo, and W), and semiconductors (qv). Useful techniques are spectrophotometry, polarography, emission spectrography, flame photometry, x-ray fluorescence, activation analysis, tracers, and mass spectrography, chromatography, and ion exchange (19) (see Analytical TffiTHODS Spectroscopy, optical Trace and residue analysis). 

If high temperatures eventually lead to an almost equal population of the ground and excited states of spectroscopically active structure elements, their absorption and emission may be quite weak, particularly if relaxation processes between these states are slow. The spectroscopic methods covered in Table 16-1 are numerous and not equally suited for the study of solid state kinetics. The number of methods increases considerably if we include particle radiation (electrons, neutrons, protons, atoms, or ions). We note that the output radiation is not necessarily of the same type as the input radiation (e.g., in photoelectron spectroscopy). Therefore, we have to restrict this discussion to some relevant methods and examples which demonstrate the applicability of in-situ spectroscopy to kinetic investigations at high temperature. Let us begin with nuclear spectroscopies in which nuclear energy levels are probed. Later we will turn to those methods in which electronic states are involved (e.g., UV, VIS, and IR spectroscopies). 

Chemical shifts also exist in X-ray photoelectron (106), X-ray fluorescence (21), and Mossbauer (123) spectroscopy. The common theme in all these phenomena is that inner electronic or nuclear energy levels are measurably affected by chemical changes in the valence electron distribution. 

Rabinowitch, E., Belford, R. L. Spectroscopy and Photochemistry of Uranyl Compounds. Internat. Ser. Monogr. Nuclear Energy, Chemistry Div., Vol. 1, New York, Macmillan, 1964... 

In common with optical spectroscopy, both classical mechanics and quantum mechanics are useful in explaining the NMR phenomenon, rho two ireai-monis yield identical relationships. Quantum mechanics. however, provides a useful relationship between absorption frequencies and nuclear energy states, w hereas classical mechanics yields a clear physical picture of the absorption process and how it is measureif. 

Mossbauer spectroscopy is based on the observation that nuclei held rigidly in a lattice can undergo recoil-free emission and absorption of X-radiation the separation of nuclear energy levels can be measured with great accuracy, and it is possible to detect weak interactions between a nucleus and its electronic environment. This may reveal the chemical state of the atom or ion, but only a few nuclei are susceptible to the effect, most work having been done with iron ( Fe) and tin Sn) and a little with ruthenium... 

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