Soft x-ray emission excited resonantly and nonresonantly by synchrotron radiation

This paper is a summary of some of the recent activities of our soft x-ray spectroscopy group. We are using soft x-ray emission spectroscopy to probe the electronic properties of matter, emphasizing atoms in the bulk and at interfaces. In particular we have used incoherent photon excitation to obtain a basic understanding of the electronic properties of a wide variety of materials such as yttrium oxide and titanium diboride, we have used the penetrating power of x-rays to study multilayers of silicon and iron and have shown that iron silicide is present in the silicon layer and provides evidence that in the antiferromagnetic Fe/Si multilayer system the FeSi2 layer is conducting rather than insulating. The ubiquitous presence of Raman scattering has been used to elucidate the electronic band structure of materials including graphite and hexagonal boron nitride. Such scattering can produce dramatic changes in the emission spectrum that can further the basic understanding of the electronic band structure. We have made a systematic study of Raman scattering in several transition metal compounds, including their borides, oxides, and sulfides. Photon-in photon-out soft x-ray spectroscopy has many applications, and is adding a new dimension to soft x-ray spectroscopy by providing many opportunities for exciting research, especially at third generation synchrotron light sources.