Demonstration of simultaneous experiments using thin crystal multiplexing at the Linac Coherent Light Source.

Multiplexing of the Linac Coherent Light Source beam was demonstrated for hard X-rays by spectral division using a near-perfect diamond thin-crystal monochromator operating in the Bragg geometry. The wavefront and coherence properties of both the reflected and transmitted beams were well preserved, thus allowing simultaneous measurements at two separate instruments. In this report, the structure determination of a prototypical protein was performed using serial femtosecond crystallography simultaneously with a femtosecond time-resolved XANES studies of photoexcited spin transition dynamics in an iron spin-crossover system.

All-diamond optical assemblies for a beam-multiplexing X-ray monochromator at the Linac Coherent Light Source.

A double-crystal diamond (111) monochromator recently implemented at the Linac Coherent Light Source (LCLS) enables splitting of the primary X-ray beam into a pink (transmitted) and a monochromatic (reflected) branch. The first monochromator crystal, with a thickness of ∼100 µm, provides sufficient X-ray transmittance to enable simultaneous operation of two beamlines. This article reports the design, fabrication and X-ray characterization of the first and second (300 µm-thick) crystals utilized in the monochromator and the optical assemblies holding these crystals.

Milli-electronvolt monochromatization of hard X-rays with a sapphire backscattering monochromator.

A sapphire backscattering monochromator with 1.1 (1) meV bandwidth for hard X-rays (20-40 keV) is reported. The optical quality of several sapphire crystals has been studied and the best crystal was chosen to work as the monochromator.

X-ray Bragg diffraction in asymmetric backscattering geometry.

We observe three effects in the Bragg diffraction of x rays in backscattering geometry from asymmetrically cut crystals. First, exact Bragg backscattering takes place not at normal incidence to the reflecting atomic planes. Second, a well-collimated (approximately 1 microrad) beam is transformed after the Bragg reflection into a strongly divergent beam (230 microrad) with reflection angle dependent on x-ray wavelength--an effect of angular dispersion.

X-ray interferometry with microelectronvolt resolution.

We demonstrate an interferometer for hard x rays with two back-reflecting sapphire crystal mirrors--a prototype x-ray Fabry-Pérot interferometer. A finesse of 15 and 0.76 mu eV broad Fabry-Pérot transmission resonances are measured by the time response of the interferometer.

Anomalous isotopic effect on the lattice parameter of silicon.

The difference Delta(a)=a(30)-a(28) of the lattice parameter of 30Si and 28Si crystals is measured over a temperature range from 4.7 to 700 K. In disagreement with existing knowledge, the strongest isotopic effect is not detected at the lowest achieved temperature T=4.