Normal Modes of Germanium by Neutron Spectrometry

The frequency wave-number relations of the lattice vibrations in germanium which propagate in the symmeiric STA100! and STAlll! directions were obtained by studying energy distributions of neutrons scattered by a germanium single crystal. The characters of the phonons were ascertained from the intensities and positions of the neutron groups in the reciprocal lattice. The methods are discussed. The results cannot be fitted by simple models using the Born-von Karman theory, but explain satisfatorily the specific heat. The far- infrared spectrum of germanium can be interpreted as combination bands in terms of the results. (auth.)

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