X ray inelastic scattering spectroscopy for electron momentum density in solids

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Compton scattering measurement is a unique method to study electron momentum density distributions in matter. This work has been done mostly at Photon Factory, National Laboratory for High Energy Physics. The results obtained are as follows;1. A high resolution Comptonspectrometer for 29.5keV incident X rays.has been constructed at Beam Line 14C. It consists of a bent crystal monochromator, a Cauchois type crystal analyzer for energy analysis of Compton scattered X rays and a sheet of Imaging Plate as a position sensitive detector. The momentum resolution is 0.09 atomic units. With this Compton profiles of Si, Al and liquid Li, Na, Li-Na alloy were measured. Information on the band structure and the effects of electron-electron correlation has been obtained. The Compton profiles of LiH, Li_2O,and Li_3N were also measured and information on the bonding electrons in these compounds has been obtained.2. At Beam Line AR-NE1 another more advanced spectrometer has been constructed. This one is for 40-80keV incident X rays and consists of a quasi doubly bent monochromator and four pairs of Cauchois type analyzer and Imaging Plate. With this Compton profiles along four different crystalline axes can be measured simultaneously. The three dimensional electron momentum density map can be reconstructed from the profiles taken along various crystalline axes to get much detailed information on the band structure and the Fermi surface geometry in metals and alloys.3. Electron-spin dependent Compton profiles of Fe and Ni single crystals were measured and compared with the band theoretical results. One of the conclusions obtained is that the momentum-wavefunctions of the magnetic electrons in these metals are well described by the band theory. It has been demonstrated that elliptically polarized synchrotron radiation X rays are quite useful to study magnetic properties of ferromagnetic materials.