Multielement spectrometer for efficient measurement of the momentum transfer dependence of inelastic x-ray scattering

Abstract

Nonresonant x-ray Raman scattering (XRS) is the inelastic scattering of hard x rays from the K shell of low-Z elements or the less tightly bound shells of heavier elements. In the limit of low momentum transfer q, XRS is determined by the same transition matrix element as is measured by x-ray absorption spectroscopies. However, XRS at higher q can often access higher order multipole transitions which help separate the symmetry of various contributions to the local density of states. The main drawback of XRS is its low cross section—a problem that is compounded for a q-dependent study. To address this issue, we have constructed a multielement spectrometer to simultaneously measure XRS at ten different values of q. By means of example, we report new measurements of the XRS from the L- and K-edges of Mg. This instrument is now available to general users at the Advanced Photon Source as the lower energy resolution inelastic x-ray scattering (LERIX) spectrometer.