74 75 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 1 / 2 2 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 1 / 2 2 Crystallography Group Joe Hriljac, Science Group Leader T he Crystallography Group comprises the High-Resolution Powder Diffraction beamline (I11), the Extreme Conditions beamline (I15), the X-ray Pair Distribution Function (XPDF) beamline (I15-1), and the Small-Molecule Single-Crystal Diffraction beamline (I19). Having these beamlines together in one science group allows us to fully exploit the technical and scientific expertise within its teams to provide the basis for future development and pioneering experiments. The past year was a second challenging one with the continuing COVID-19 pandemic, but especially so for beamlines that were undergoing large upgrades that started pre-pandemic such as I11 and I15-1. These both did progress significantly and are near to completion, but many delays occurred due to staff shortages and supply chain issues and the knock-on effects these had on project planning. Thankfully these did not impact the purchase, installation and commissioning of new detectors and so those for I15 and I19 went more to plan and are now fully operational. The other project that has been delayed is the upgrade to the I15/I15-1 wiggler as engineers were not able to come from abroad to do the intended works. Parts have arrived and the upgrade should be completed in summer of 2022. Due in large part to the hard work and dedication of the beamline and technical staff to continue supporting remote user experiments, the user programmes on all beamlines have moved closer to pre-pandemic levels and 185 papers were published during the 2021 calendar year from data attributed to the four beamlines. I11 update The high brightness beamline uses monochromatic X-rays in the range of 6 - 25 keV for high-resolution and time-resolved powder diffraction experiments in the first Experimental Hutch (EH1) or for Long Duration Experiments in EH2. The varied science programme supports a wide range of studies by chemists, physicists, materials scientists and environmental scientists in particular for non-ambient applications and experiments requiring unusual hardware setups such as toxic/corrosive gas absorption studies at cryogenic temperatures, resonant diffraction at high temperature and time-resolved in operando lithium-ion (Li-ion) battery work. After running for over ten years, many components such as the monochromator, diffractometer and Multi-analyser Crystal (MAC) detector began to show signs of wear. An upgrade plan, endorsed by the Scientific Advisory Committee (SAC) and the Diamond Industrial Science Committee (DISCo) at the end of 2017 to replace these components started in 2019 and the new Newport diffractometer was partly installed when site was shut in March 2020. During the course of the remainder of 2020 the installation and commissioning resumedwhen possible under the COVID-19working protocols. Finally in January 2021 the last stage, commissioning of the robot sample changer, was completed and the beamline became operational again. Since that point a large number of more routine experiments have been conducted by remote user access with beamline staff assistance and, more recently, users have returned to site. When all restrictions have been removed the full experimental programme will resume – until now some experiments are still not scheduled as they require setups that require too many people in small, enclosed spaces. The construction of a new PSD using Mythen3 technology is well underway with hopes for completion, testing and commissioning in 2022. This will lead to the ability for even faster collection of powder patterns for, e.g., time-resolved studies. I15 update The Extreme Conditions beamline, I15, employs high energy X-rays to explore the structure of materials at high pressures, high and low temperatures, as well as other in situ and in operando conditions. The beamline receives an X-ray continuum from the superconducting wiggler; this allows for experiments that require monochromatic X-rays between 20 and 80 keV, as well as polychromatic beam. I15 was originally designed to serve the mineral physics community, which it has, whilst also assisting material scientists, chemists and solid-state physicists with their structural investigations, at pressure or otherwise. I15 continues to offer extensive capabilities and support to users to assist their high-pressure studies. I15 users have pre-experiment access to bespoke assistance and training from our highly skilled staff in diamond anvil cell (DAC) preparation and loading, as well as the usage of beamline DACs for novice users for I15 experiments. The high-pressure gas loader available at I15 offers users the choice of many possible gases to use as their pressure transmitting media (PTM), allowing them to optimise for hydrostaticity with helium or neon, or choosing a PTM based on desired interactions with the sample at pressure. Work is underway to add hydrogen to our gas loading capabilities, originally scheduled for 2020 this has had to be pushed back into 2022 due to the pandemic. The recent addition of the laser heating system adds a further unique capability – the I15 system is capable of quickly ramping the laser power to perturb a sample without delivering too much heat to the bulk. A DECTRIS PILATUS3 X CdTe 2M arrived in late 2020 and is now in routine use with 14 user experiments having used it in 2021. It provides much greater sensitivity to high-energy X-rays and the capability for much faster data collections. The quality of data has led to a resumption of the development of high-pressure single crystal data collection including the project of a Diamond PhD student. Further upgrades to I15 to take full advantage of fast hardware-based scanning and mapping are planned. I15-1 update The XPDF beamline, I15-1, is dedicated to producing high-quality X-ray scattering data for Pair Distribution Function (PDF) analysis. Operational since 2017, I15-1 has illuminated samples from diverse fields, from Earth sciences to pharmaceuticals, as well as material science and chemistry. XPDF receives X-rays from the inside edge of thewiggler fan, and this light is monochromated and directed to the end station in three energies: 40, 65 and 76 keV. PDF data are collected at high energies to produce the low sample absorption and high Q-range required for successful interpretation. Gaining structural information on amorphous samples is a primary goal of many XPDF experiments, but crystalline samples can also display local structure variations such as defects and disorder, which can be studied via PDF analysis. PDF data collections are rarely available at home institutions, so in order to allowmore people to exploit this powerful technique I15-1 complements the standard proposal route with popular Rapid and Easy Access routes, where PDF data can be collected via a mail-in procedure. Consisting of a sample position, with an optional sample-changing magazine, and two large area detectors, the end station is highly flexible and has been adapted to many in situ and in operando experiments, including variable temperature, gas flow, hydrothermal synthesis and electrochemical cycling. For more routine measurements, the 15-position sample changer has been a popular choice, allowing automatic data collection. Further upgrades, including a new end station and a sample-changing robot with 400 positions, progressed during 2021 and these are now in use. The final aspect of the current upgrade is a new detector based on CdTe sensors that will be much more sensitive at high energy and with faster electronics for data readout. Construction has progressed and the detector is currently in the testing stage with an expectation that it will be commissioned on the beamline in 2022. These upgrades will be a synergistic addition to the existing autoprocessing infrastructure and will allow users to collect better data with less manual intervention. I19 update The Small-Molecule Single-Crystal Diffraction beamline, I19, uses X-rays in the 5 – 25 keV energy range to determine the structures of small-molecule and extended three-dimensional systems, e.g. Metal-Organic Frameworks, with single-crystal diffraction techniques. These methods can be applied to the characterisation of novel materials or for investigating the variation in the structure of a crystallinematerial under an external physical influence such as a change in temperature, the exposure to a gas, photo-excitation or through the application of high-pressure. The use of the robotic sample changer, and remote access, is now well established in Experimental Hutch 1 (EH1) of the beamline, where premounted samples are sent to Diamond under cryogenic storage, and users then run their beamtime from their home institutions. This mode of operation makes it possible to carry out chemical crystallography studies in a more responsive manner as beamtime can be scheduled in more regular, and shorter, periods. We now schedule individual shifts, rather than whole one-day (three shifts) blocks of beamtime, for those wishing to run their beamtime via the remote access route. For Experimental Hutch 2 (EH2), we have recently developed a cell which allows a high static electric field to be applied to the sample crystal. The application of electric fields to materials can result in a variety of responses that may have important technological applications, spanning electronic and ionic conductivity to piezo- and ferro-electricity. In 2021, the original mirrors were replaced with much improved quality ones that were no longer needed on I04. These are giving much improved performance in both beam focus and positional stability. During 2021 a DECTRIS EIGER2 X CdTe 4M was installed in EH2 and this is now in regular use producing vastly superior data over the older system. The Crystallography Science Group members. Having these beamlines together in one science group allows us to fully exploit the technical and scientific expertisewithin its teams to provide the basis for future development and pioneering experiments.