COMPTON-SCATTERING AND THE STUDY OF ELECTRON MOMENTUM DENSITY DISTRIBUTIONS

The Doppler-broadening experienced by photons Compton scattered from b ound electrons allows the momentum distribution of the target to be pr obed. The Compton profile so obtained turns out to be sensitive to the wave-mechanical description of the scatterer and has therefore been e xploited, for example, to check band theoretical models of solids, to identify electron correlation effects and most recently to extract Fer mi surface topography. The technique has suffered from the low photon energy and lack of monochromaticity of X-ray tube sources and the weak ness of gamma emitting isotopes. Both these problems have been circumv ented with the use of synchrotron radiation which has the added benefi t of allowing spin densities to be studied through the extraction of c ircularly polarised photons. In this paper the interpretation of Compt on line-shapes within the Impulse Approximation will be discussed and illustrated with a selection of recent results. (C) 1997 Elsevier Scie nce Ltd.