Oxidised porous silicon emits luminescence in two distinct bands in the visible region. The fast blue (τ ∼ ns) and slow red (τ ∼ μs at 300K) bands are studied via the separate methods of time-resolved XEOL in single-bunch mode and wavelength-selective and total XEOL in multi-bunch mode. Measurements have been conducted at the silicon K-edge (1840eV) and L2,3-edge for freshly prepared and oxidised porous silicon and related samples. Both methods give conclusive evidence that the fast, blue luminescent site is defects in silica or suboxide formed near to the Si/ SiO2 interface, whereas the slower, red band originates from smaller silicon particles of diameter 14Å or less found in porous silicon. The XEOL process is discussed and range estimates of the spatial separation between the photoionisation event and radiative recombination are made.

The energy dependence of the magnetic Compton cross-section was measured with elliptically polarised synchrotron radiation at five energies from 245.2 to 1000.5 keV at the European Synchrotron Radiation Facility (ESRF) using a recently installed superconducting wavelength shifter, the sample was ferromagnetic iron. These measurements more than double the highest photon energy previously used in synchrotron radiation studies. It was found that the integrated intensity of the spin-dependent scattering was well described by the formulae for the differential cross-section, dσ/dΩ, for free, stationary electrons. The optimisation of experiments designed to yield the spin-dependent Compton profile from the double differential cross-section, d2σ/dΩ dω is discussed.

The spin density in the Heusler alloy Cu2MnAl, has been studied in a Compton scattering experiment with 92 keV circularly polarized synchrotron radiation on the high-energy beamline at ESRF. The conduction electrons were found to have a negative spin polarization of 0.4 μB which is at variance with the deduction of a positive moment from earlier neutron data; neither was any evidence found for a 3d spin moment on the copper site. The spin moment on the Mn site at room temperature was determined as 3.25 μB, which is in agreement with neutron data. The spin-dependent Compton profiles for the [100], [110] and [111] directions, reported here, show anisotropy in the momentum density which is in good agreement with new KKR calculations based on a ferromagnetic ground state. By combining charge- and spin-dependent Compton data the momentum space anisotropies in the majority and minority bands have been analysed. Both the majority and minority spin densities are anisotropic.