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Fw: Mossbauer spectroscopy?

Hello Jim and List,

Mossbauer spectroscopy is an analytical technique built upon the fact that
certain nuclides, when locked into a crystal lattice below a lower
temperature threshold, emit gamma rays (electromagnetic radiation shorter in
wavelength than x-rays) in a unique fashion.  The crystal structure absorbs
recoil momentum of the emitting nucleus, making the recoil negible because
of the large number of atoms in the lattice and the energy being absorbed by
the crystal structure.  This means there is virtually no loss of energy by
the emitted gamma photons.  The emitted photon is sharply defined by its
very narrow energy spread.

The the Mossbauer spectrometer has a the gamma ray source is on a moving
platform and the specimen to be studied is located in a fixed position
nearby.  A dector measures the gamma rays scattered by the sample as the
gamma ray source source is moved slowly towards the sample.  The emitted
radiation varies in frequency due to the Doppler effect.  The frequency
indicates resonance absorption in the sample nuclei.  This can give info
about the bonding and structure of the compounds making up a crystal lattice
because chemical shifts in the resonance energy are produced by the
pressence of the surrounding atoms.

Steve
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Steven Excell
Seattle, Washington USA
E-Mail: excell@concentric.net
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