2XC Double-Axis Powder Diffractometer

The primary function of the 2XC instrument is to extend the accessible q-range that is measurable for diffraction at MURR to lower values, and, thus, providing access to slightly larger periodic spacings.

The 2XC is a two-axis diffractometer that utilizes a set of five equally spaced 3He detectors for increased acquisition rate. This instrument specializes in the study of solids with comparatively long lattice spacings (~8-12Å). It employs long wavelength neutrons (λ=4.356Å) so that low-Q Bragg peaks appear at higher 2θ angles where the background is lower relative to that of more typical diffractometer wavelengths of 2.35Å or 1.5Å. It uses a multi-Soller detector system and vertically focusing monochromator (either PG (002) or Cu (220)). Over the years, investigations of hydrocarbons adsorbed on graphite, ordered biological systems, soft films, and others have been carried out. More recently, 2XC has been applied to the study of hydrogen storage materials. A gas handling system and pressure cell have been developed specifically for use on the MURR beam line instruments.

Researchers have used the 2XC instrument for several areas:

• Hydrogen storage materials, especially graphene oxide frameworks (GOFs)

• Multilayers of lipid bilayers

• Two-dimensional ordering of alkane molecules

• Monochromators: PG(002) (λ=4.356 Å) or Cu (220) (λ=1.278 Å) (both vertically focusing)

• Filter: Cooled beryllium

• Detectors: Five 3He proportional detectors with an angular spacing of 15° between each other

• Collimation: Source-Monochromator: 54´

Monochromator-Sample: 33´

Sample-Detectors: 40´

• Sample environment: Low-temperature sample environment