NSLS-II Seminar

To date, silicon is the primary material for x-ray crystal optics.
Well-established silicon crystal growth methods and processing techniques offer high quality diffracting elements with customizable crystallographic orientation. This flexibility is the key towards realization of millielectronvolt-resolution x-ray monochromators and analyzers for x-ray spectroscopy.

However, silicon is inferior to diamond in terms of thermal conductivity, radiation hardness and thermal expansion. These are key aspects for high-heat-load applications of diamond in x-ray crystal optics, which become increasingly important at fourth-generation synchrotron sources.
Furthermore, recent studies have shown that diamond is indispensable for realization of x-ray free-electron laser oscillator (XFELO), a highly anticipated future source of fully coherent x-rays of the highest brightness. Diamond crystals can play the role of high-reflectivity x-ray mirrors of the XFELO optical cavity.

Realization of the XFELO requires x-ray diffraction studies of diamond crystals with millielectronvolt resolution. This talk, presents an overview of recently developed x-ray optical instruments and methods for routine characterization of diamond x-ray mirrors. Several schemes are discussed which enable measurements of diamond reflectivity for different Bragg reflections and ultraprecise measurements of thermal expansion