Multilayer X-ray optics at CHESS

Abstract

Almost half of the X-ray beamlines at the Cornell High Energy Synchrotron Source (CHESS) are based on multilayer optics. ;Traditional' multilayers with an energy resolution of DeltaE/E approximately 2% are routinely used to deliver X-ray flux enhanced by a factor of 10(2) in comparison with standard Si(111) optics. Sagittal-focusing multilayers with fixed radius provide an additional factor of 10 gain in flux density. High-resolution multilayer optics with DeltaE/E approximately 0.2% are now routinely used by MacCHESS crystallographers. New wide-bandpass multilayers with DeltaE/E = 5% and 10% have been designed and tested for potential applications in macromolecular crystallography. Small d-spacing multilayers with d < or = 20 A have been successfully used to extend the energy range of multilayer optics. Analysis of the main characteristics of the Mo/B4C and W/B4C small d-spacing multilayer optics shows enhancement in their performance at higher energies. Chemical vapour deposited SiC, with a bulk thermal conductivity of a factor of two higher than that of silicon, has been successfully introduced as a substrate material for multilayer optics. Characteristics of different types of multilayer optics at CHESS beamlines and their applications in a variety of scattering, diffraction and imaging techniques are discussed.

Scherrer grain-size analysis adapted to grazing-incidence scattering with area detectors

“…, this smearing can usually be neglected; however, for multilayer optics with in the range 0.5-2% (Kazimirov et al, 2006), it definitely has to be taken into account.…”

Modeling of heat-bump formation in x-ray optics under SR beams

“…[1], and in the case of the multilayers optics the SiC substrates with higher heat conductivity, as reported by Kazimirov et.al. [2], are used to mitigate this problem. The effect of high heat load most often studied by its direct effect on the diffraction process by observing variation of the rocking curve with the increasing heat load.…”

Improved thermal stability of Mg/Co multilayer by introducing Zr barrier layer

“…In extreme ultraviolet (EUV) region, high reflective multilayer mirrors (MLMs) are widely used as optical elements for applications such as EUV microscopy [1] , high harmonic femtosecond chemistry [2] , solar astrophysics imaging [3,4] , and synchrotron radiation [5] . In the 25-40 nm wavelength region, Mg-based multilayers, such as Mg/SiC, Mg/Y 2 O 3 and Mg/Co are promising for Mg L 3 absorption edge is located at 25nm [6][7][8][9][10][11] .…”