Photon excitation for satellite-free X-ray spectroscopy: Instrumentation challenges

Soft X-ray emission spectra (SXES) obtained using monochromatic synchrotron radiation (SR) provides important advantages as compared with electron excitation. Photons can penetrate deep into the sample providing nondestructive information from bulk samples. With availability of tunable monochromatic photons from synchrotron sources, it is now possible to selectively ionize core electrons near enough to the core level threshold energy producing singly ionized atoms and molecules resulting in satellite-free X-ray emission spectra. This offers the ability to separate satellite structure from diagram lines and also allows more detailed studies of the satellite processes. Recent developments in satellite-free SXES will be reviewed along with instrumentation challenges in utilizing the small phase-space attributes of high brightness from third-generation SR sources producing soft X-ray and vaccuum ultraviolet wavelengths. (orig.)