Bill Marshall started his scientific career at the Soil Survey of England and Wales at the then Rothamsted Experimental Station in the mid-1980s. Bill joined a small analytical lab as a technician and undertook a wide range of physical and chemical analyses of soil samples derived from the Soil Survey's field mapping programme as well as various research projects. As part of the regime that existed at Rothamsted at the time, Bill was offered ‘day release’, opting for a degree at Birkbeck College in Physics. The work of the Soil Survey came to an abrupt end in early-1987 and Bill was made redundant, later joining the Chemistry Department at Birkbeck College as a technician in the Mossbauer group with Brian Fitzsimmons.
Like all Birkbeck undergraduates, Bill was a part-time student. Teaching was in the weekday evenings from 18:00-21:00, with laboratory classes on Saturdays. He was an exceptionally clever student, and his first class degree in 1987 was fully deserved. He continued at Birkbeck as a PhD student, funded by a studentship from the Institut Laue-Langevin (ILL), under the supervision of Keith McEwen, who was Head of the Physics Department, and Amir Murani at the ILL. His research project was centred on inelastic neutron scattering on rare-earth and uranium intermetallic compounds showing heavy fermion behaviour, with experiments carried out at the ILL, ISIS and the Risø Laboratory in Denmark.
Bill joined Richard Nelmes’ research group at the University of Edinburgh as a postdoc at the start of 1994. He came into what was by then an already well-established collaboration between Richard Nelmes and Michel Besson in Paris, in a project to extend neutron diffraction to much higher pressures. It was quickly clear that Bill had exceptional abilities, and he soon made an impact on the key problems relating to data corrections for the complex near-sample geometry and calibration of the exact true positions of all detector elements. The latter is essential to perform the highly path-dependent corrections, and whose value has been enduring in allowing effective work with liquid and amorphous samples. In 1995, work began on the design and construction of the PEARL diffractometer at ISIS, an instrument optimised for high pressure studies of materials under high pressures. Bill was much involved from the start in the detailed design of all parts of the instrument and its installation, and in the latter part of the project he took over all of the day to day project management, oversaw the installation on the beamline, and took charge of the extensive commissioning that then followed. Its subsequent success owes much to his high skills, exceptional care and dependability, and hard work. It was fitting that Bill then moved to ISIS in early 1998, joining the ISIS Crystallography Group as Instrument Scientist on PEARL.
Over the following 17 years, Bill led the scientific and technical programme in high pressure diffraction at ISIS, establishing the PEARL diffractometer as the world-leading facility for crystallographic studies over a wide range of pressure and temperature conditions using neutrons. Its success is demonstrated by the many publications in high impact journals, which cover important fields such as earth/planetary science, ice physics, energetic materials, magnetic ordering and functional ceramics. In addition to his dedication whilst providing high quality ‘local contact’ support to external research groups on PEARL, Bill established a number of highly successful research collaborations, principally in the field of phase transitions within molecular systems. These included projects with the University College London, the Universities of Edinburgh, Strathclyde and Keele and with Diamond, and resulted in a number of successful PhD studentships. One of Bill’s particular skills lay in extracting the maximum structural information from the (often limited) neutron diffraction data obtained from a sample within the complex pressure cell, whether solving the crystal structures of new high pressure polymorphs or probing subtle changes in the chemical bonding between molecules during compression. Bill’s knowledge and dedication to continually strive to improve the capabilities of the PEARL diffractometer also covered a number of important technical developments, including the ability to rapidly cool samples held at high pressure and the use of new materials within the pressure cells. In the latter case, his pioneering use of a new high strength, low attenuation ceramic led to significant improvements in data quality and reductions in cost.
Bill’s funeral was held at South Oxfordshire Crematorium and Memorial Park on Wednesday 28 October. His family were joined by many past and present colleagues from ISIS, and several of his university collaborators. He will be fondly remembered, and sadly missed, by all.