Accession Number : AD0608416

Title :   PHYSICS OF THE MOSSBAUER EFFECT.

Descriptive Note : Physical Sciences Research Papers,

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

Personal Author(s) : Eyges,Leonard J.

Report Date : OCT 1964

Pagination or Media Count : 40

Abstract : This paper considers from a simple physical point of view the Mossbauer effect, i. e., the 'recoilless emission' of gamma-rays from a nucleur bound in a crystal lattice. It begins with a discussion of the kinematics of gamma-ray emission from such a nucleus. The idealized case of a massive 'lattice' characterized by a single frequency and the more realistic one and three-dimensional models are treated. We point up the fact that in the Mossbauer effect the lattice as a whole (the lattice center of mass) always recoils after photon emission, so that the term 'recoilless emission' is in one sense misleading. We emphasize that the essence of the Mossbauer effect is not photon emission without recoil, but rather is photon emission without transfer of energy to internal degrees of freedom of the lattice. Using the basic ideas of quantum mechanics, namely, the rules for the manipulation of probability amplitudes (the socalled 'transformation theory'), we calculate the probability for recoil without excitation of internal degrees of freedom, i. e., the Mossbauer f-factor, on the assumption that the individual photon emissions, consequent lattice recoil, are instantaneous. In Appendix A we discuss this question of instantaneous emission in some detail, and show how it is not in contradiction with the fact that the nuclear transition that leads to the gamma-ray emission has a finite half-width. In Appendix B those rules of transformation theory that are used in the body of the paper are summarized. (Author)

Descriptors :   (*MOSSBAUER EFFECT, NUCLEAR PHYSICS), GAMMA RAYS, CRYSTAL LATTICES, NUCLEI, PROBABILITY, PHOTONS

Distribution Statement : APPROVED FOR PUBLIC RELEASE