Recoilless nuclear resonance absorption fluorescence

Rudolf Mossbauer, while working on his Ph.D. thesis, carried out experiments of this kind with lr. But surprisingly, on lowering the temperature he found an increase in the absorption effect rather than a decrease. Mossbauer was able to explain this unexpected phenomenon, and was awarded the Nobel Prize in 1961 for the observation and correct interpretation of the recoilless nuclear resonance absorption (fluorescence) which is now known as the Mossbauer Effect and which provided the basis for a powerful technique in solid state research. 

The Mossbauer effect involves the resonance fluorescence of nuclear gamma radiation and can be observed during recoilless emission and absorption of radiation in solids. It can be exploited as a spectroscopic method by observing chemically dependent hyperfine interactions. The recent determination of the nuclear radius term in the isomer shift equation for shows that the isomer shift becomes more positive with increasing s electron density at the nucleus. Detailed studies of the temperature dependence of the recoil-free fraction in and labeled Sn/ show that the characteristic Mossbauer temperatures Om, are different for the two atoms. These results are typical of the kind of chemical information which can be obtained from Mossbauer spectra. 

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