Beamline Guide

Introduction

I16 is a high flux, high resolution, hard X-ray beamline at Diamond Light Source Ltd.

The high flux on this beamline is essential for two key categories of study:

• measurements of very weak, but increasingly important, scattering processes, such as diffraction from magnetic, charge and orbital ordering;
• measurements on very small samples volumes, including artificial nanostructures, thin films and surfaces.

The intense, low-divergence undulator beam can be focused to a spot less than 50 by 200 microns, with an energy range that is continuously tuneable from 3.3 keV (below the uranium M-edges) to around 15- 25 keV depending on the optical configuration. Energies in the range 2.7-3.0 keV are now available but require a non-standard set-up to reduce air absorption and should be discussed with beamline staff.

A diamond crystal phase retarder is available to convert the linearly polarised X-ray beam to circular polarisation.

The large 6-circle kappa diffractometer supports several sample stages, giving temperatures down to ~4-6 K, and a wide variety of detectors including an in-vacuum Pilatus 100K photon-counting area detector. The diffractometer can operate in horizontal or vertical scattering geometries, or even mixed modes allowing fixed-alpha surface scattering measurements.

Linear polarisation analysis can be achieved with a novel in-vacuum analyser stage. A variety of analyser crystals can be installed to best match the energy and sample required.  A high resolution in-vacuum Quad-Merlin detector sits on the analyser stage and can also be used for measurements of coherent diffraction.

A double-bounce silicon harmonic rejection mirror system provides exceptionally high harmonic rejection over a wide energy range.

Standard Beamline Sample Stages

• 4K-300K ARS GM cooler (base temperature is typically ~6K but may be lower when pointing down).
• 6K-800K ARS GM cooler (base temperature typically 8K; usually assume a maximum temperature of ~600K)

The following may be available by arrangement:

• Oxford Diffraction Cryostream cooler (~100K-300K)
• CryoIndustries Helium gas jet cooler (~15K-300K) (Note that this unit is more susceptible to icing than the Oxford unit).
• 1.0-1.5 T electromagnet
• KB microfocus mirrors (focus down to a few microns)
• Pilatus 2M detector sitting in horizontal scattering plane with control of detector distance from 0.5 - 2m.
• Controllable electric fields upto 5 kV with arbitary waveform
• Razorbill strain cell for automated uniaxial strain measurments in the cryostat. Max displacement ~ 6um, max force ~ 45N dependent on sample.