Professor John White was a key figure in the international scientific community for more than five decades. Over the course of a long and distinguished career, through a combination of advances in experimentation and choice of paradigm examples, his work demonstrated how neutron scattering data could be analysed to provide precise details of molecular structure and dynamics for a wide variety of chemical systems.
John sadly passed away in August 2023. To celebrate and commemorate his lasting contributions, a symposium is being organised in his honour. We welcome contributions from John’s colleagues, collaborators and enthusiasts in what will be a celebration of a life well lived.
The video recordings of the talks are now available to watch on YouTube at the following links, grouped into the following sessions :
To access the full playlist you can click here.
John came to Oxford in 1960 on an 1851 Fellowship to do a doctorate in the area of magnetic resonance with Rex Richards. Within 5 years he had completed his doctorate, obtained a full university post, and started a research programme using the very new techniques associated with the scattering of neutrons.
John’s early neutron research was done at the reactors at Harwell from about 1963 onwards but discussions had begun in Europe on the possibility of building a high flux reactor with more advanced capabilities. John played a significant part in the preliminary scientific discussions and an agreement was signed in 1972 for Britain to participate as an equal partner with France and Germany in the Institut Laue Langevin (ILL). John was appointed to be the first full British director of ILL (deputy director in 1975-7, and main director 1977-80). During his first 12 years of neutron research John not only made substantial steps forward in his own research but also drew others from a range of different fields in on the act. John’s early neutron research in this area was also a significant factor driving the decision to create the neutron spallation source (ISIS) at the Rutherford.
John’s research covered a wide range of structural and dynamic phenomena in physical chemistry, e.g. protein structure and dynamics, surface chemistry, and colloids, and his contribution helped to give Europeans an unusual advantage in this field over their American counterparts. In 1985 John left Oxford to return to Australia, where he contributed to a similar strong advance in neutron scattering science.
I was one of John’s first undergraduate students in the early summer of 1963. However, my introduction to neutron scattering did not start until 1975, when John appointed me to supervise his group on Oxford while he was an ILL director.
Reflections on John White’s Contributions to Australian Science, together with his Role in Enhancing Pan-Asian Collaboration
John was born near Newcastle in New South Wales, and got his start in science at Sydney University. He returned to Australia in 1985 and joined the Research School of Chemistry at the Australian National University, where he remained until his death last year.
John’s most significant contribution to Australian Science, in my opinion, has been his role in getting both the OPAL Neutron Source (in Sydney) and the Australian Synchrotron (in Melbourne) funded by governments, and built to the highest international standard. Another mark of John’s career is the talent that he has nurtured and grown, both while at Oxford and also at the Australian National University in Canberra, where he has played a leading and influential role for the last 40 years or so.
He was a Fellow of the Australian Academy of Science, and of the Royal Australian Chemical Institute (and was its President). He was a member of ANSTO’s Bragg Institute Advisory Committee from the beginning, and its chair between 2008 and 2011. He was President of the Australian Institute for Nuclear Science and Engineering between 2005 and 2006, in the crucial time that the OPAL Research Reactor first started and the relationship between ANSTO and AINSE changed in a major way. He was instrumental in setting up the prestigious AINSE Research Fellowship scheme, which for a number of years ensured that bright young researchers were able to nucleate new groups in the Australasian universities, to complement and make optimal use of the capital investment in OPAL. John was the second President of the Asia-Oceania Neutron Scattering Association, and was one of the leading players in its formation. In 2015, he was awarded the AONSA Prize in recognition of his leading role across the Asia-Pacific. Most significantly he was also chair for many years (2002-2012) of the International Advisory Committee for the J-PARC Japan Proton Accelerator Research Complex, the other leading facility (along with OPAL) of its type in the Asia-Pacific region.
I will try to summarise John’s contributions to Australian science, along with his crucial role more broadly in the Asia-Pacific region. And I will include some interesting and amusing anecdotes, from this time, that the audience may not have heard before.
In 1964 John White was a fellow of St Johns College Oxford working with Rex Richards on electron nuclear double resonance spectroscopy (ENDOR). A recent chance meeting with Peter Egelstaff from AERE Harwell had interested John in the uses of neutron scattering spectroscopy in chemical sciences, and particularly in the possibilities of using deuterium labelling. At the time Julia S-D (now Julia Higgins) was a final year physics undergraduate in Somerville College, Oxford looking for opportunities to study for a DPhil. Her tutor introduced her to John and, believing a physicist was more likely to take to neutron scattering than a chemist, he offered her a studentship despite her chronic lack of experience in chemistry. Thus some 60 years ago (almost to the day) began two long careers using this novel technique. The presentation will describe the experimental design and initial results, noting how a physicist successfully grappled with deuterating her own samples. It will then briefly mention the next steps they each took in their long careers in the field, how their scientific interests diverged and set them on their subsequent paths.
Throughout John White’s long career, he provided inspirational leadership in the UK, Europe and in his native Australia, expanding the frontiers of Neutron Scattering from its traditional physics focus to address wider problems in chemistry and soft matter science.
As Director of ILL, he successfully led the instrument renewal programme – the ‘deuxieme souffle’ – expanding the use of cold neutrons. On his return to Australia, he promoted strong engagement with the ISIS facility in the United Kingdom through Australian development of the SURF reflectometer.
He was active in fostering collaboration in the Pacific region, particularly in Japan through his long-term chairmanship of the International Advisory Committee of J-PARC – Japan’s multidisciplinary accelerator-based research facility.
His career was marked by developing and inspiring successive generations of research leaders, whose impact continues to be felt far and wide.
Photographic glimpses of the neutron-related life I shared with John over almost 60 years
I joined John’s group at the Research School of Chemistry (RSC), Australian National University, Canberra in the mid 1990’s. Here I was quickly introduced to x-ray scattering from interfaces followed by the application of neutron scattering to the same systems. Australia’s first X-ray Reflectometer capable of studying free liquid surfaces had been built using the Elliott GX-13 fine focus rotating anode source in Prof. White’s laboratory. This became an important resource and stepping stone to synchrotron and neutron studies of interfacial structure for many Australian researchers. This was a common theme of John’s work, that of training and providing opportunity for researchers at any stage of their career. This presentation will follow the progression from the study of surfactant self assembly / templating at interfaces, biomolecules at interfaces and the development of model cell membranes with x-ray and neutron scattering as the undergirding techniques.
Hydrated uranium(VI) oxyhydroxides will be an important mineral group within the alteration phases formed during the corrosion of spent nuclear fuel, in the case where groundwater has entered a breach in the fuel cladding. By controlling the addition of base to an aqueous uranyl solution, we have shown that crystalline films of layer lattice uranium oxyhydroxides can be grown on silicon [1] or conductive glass under nonhydrothermal conditions. The structures of these minerals are based on sheets of uranyl polyhedra with cations distributed between the sheets or, where the sheets are electrostatically neutral, solely water exemplified here by the mineral metaschoepite.
The crystallographic textures of two films, metaschoepite and a lanthanum-intercalated phase, were studied by grazing incidence wide-angle X-ray scattering (GIWAXS) up to 200 °C. The X-ray data are supported by SEM-EDS measurements before and after thermal evacuation, as well as thermogravimetric analysis of powders in air up to 800 °C. The higher desorption temperatures required to remove molecular water, and the enhanced stability of the lanthanum-intercalated phase against collapse compared with metaschoepite are consistent with La(III)-water interactions and La(III)-hydrate layers that kept apart the uranyl polyhedral sheets.
With the new Radioactive Materials Beamline available at the Shanghai Synchrotron Radiation Facility, we intend to complement our X-ray diffraction data on uranium oxyhydroxide films to explore the local interlayer site structure and composition for incorporated fission products, in the frame of heat-generating high-level radioactive waste for an engineered deep geological repository.
[1] X. Gong, Q. Tian, J. Li, J. Wang, M. Yan, and M.J. Henderson, Appl. Surf. Sci. 615 (2023) 156307.
Despite recent attention to nanoplastics, there is still much to learn about their surface coatings that give them their “bioidentity”, which is critical to their behaviour in biological contexts. These coatings, corona, form on the particle as a complex mixtures of proteins and other surface-active chemicals – some strongly bound, and others weakly attached and exceptionally hard to study– which depend on both the particle and its environment.
We show that the nature of the protein corona in simple systems depends on the surface charge and particle size of the nanoplastics, and that nanoparticles with corona can aggregate to form higher order structures, which may trigger biological stress responses. We also show that model nanoplastics strongly associate with human alveolar epithelial cells, in a manner dependent on their protein corona.
However, there is much still to be learnt about the impact of complex environmental systems on these coatings, which is critical to the development of mitigation strategies for nanoplastic contamination.
Although Dr. John White’s research focused mainly on using Small Angle Neutron Scattering, we are honoured to dedicate this science revealed on Cold Neutron Triple Axis Spectrometer SIKA at ANSTO to Dr. John White for his support and guidance during the construction of SIKA and the establishment of Taiwan Neutron Scattering Society (TWNSS).
In the search for green energy, thermoelectric material has been demonstrated to be a promising material for the generation of electricity from waste heat recovery without pollution waste. The most essential factor for a material to possess effective thermoelectric character is the low thermal conductivity to maintain a temperature gradient over the material for long last thermal electrical transport. This presentation focus on using a neutron triple-axis spectrometer to answer the key questions linked to the functionalities of thermoelectric materials. One of the key factors for effective thermoelectric performance is a low lattice thermal conductivity that frequently links to the limitations on lattice vibrations.
Phonon dispersions measured using inelastic neutron scattering cover the entire Brillouin zone reveal very strong electron-phonon and phonon-phonon scattering leading to a huge softening of the phonon energies, extremely short phonon lifetimes in the order of 5 ps, extremely short phonon propagation lengths in the order of 5 Å, and negative group velocities at large wavevectors for the acoustic phonons in a 8%-Sb-and-6%-Bi codoped Ge0.86Sb0.08Bi0.06Te. It is the very short phonon lifetimes that giving rise to the low thermal conductivity observed at temperatures as high as 800 K. The very limited phonon propagation length together with the negative phonon group velocity at large wavevectors that restrict heat transport, which explains the origin of the poor thermal transport as a result of a very strong electron-phonon scattering in Ge0.86Sb0.08Bi0.06Te.
It has been known for almost one hundred years that a lower surface tension can be achieved at the air–water interface by spreading protein from a concentrated solution than by adsorption from an equivalent total bulk concentration. Nevertheless, the factors that control this nonequilibrium process have not been fully understood. In the present work, we apply ellipsometry, neutron reflectometry, X-ray reflectometry, and Brewster angle microscopy to elaborate the surface loading of human serum albumin in terms of both the macroscopic film morphology and the spreading dynamics. We show that the dominant contribution to the surface loading mechanism is the Marangoni spreading of protein from the bulk of the droplets rather than the direct transfer of their surface films. The films can be spread on a dilute subphase if the concentration of the spreading solution is sufficient; if not, dissolution of the protein occurs, and only a textured adsorbed layer slowly forms. The morphology of the spread protein films comprises an extended network with regions of less textured material or gaps. Further, mechanical cycling of the surface area of the spread films anneals the network into a membrane that approach constant compressibility and has increased durability. Our work provides a new perspective on an old problem in colloid and interface science. The scope for optimization of the surface loading mechanism in a range of systems leading to its exploitation in deposition-based technologies in the future is discussed.
Nanoparticle-protein complexes comprising silica or cadmium sulfide nanoparticles with human proteins have been detected with high sensitivity at the air-water interface using X-ray and neutron reflectivity measurements and ellipsometry. For the interaction between β-casein and 8 nm silica particles the sensitivity of the reflectivity signal at the air-water interface has been shown by X-ray reflectometry to be pico-molar. This high sensitivity results from the nanoparticle-protein interaction which generates surface active complexes. The interaction between human serum albumin and cadmium sulfide nanoparticles has been detected using neutron reflectometry and tracked kinetically by ellipsometry. Here we have shown that lateral domains or aggregates in the surface monolayer change in size or dissipate over the course of several hours. The three methods of monitoring the protein-nanoparticle interaction during film evolution are discussed.
In March 1994, not long after starting my PhD, John White, my then supervisor, asked me “do you have a passport”? On 27th May I was off to ISIS for an experiment on LOQ and then on CRISP! This was the start of a series of neutron scattering experiments during my PhD but much more broadly an introduction to a network of interesting scientists, top level facilities and exciting science that continues to influence my work. I will discuss some of the still ongoing work on micelle templating that was started during my PhD and some of the advances and new directions we have charted since then.
Experimental scattering methods, primarily X-ray and neutron, can reveal insight into the structure and dynamics of condensed matter systems, an area in which Professor John White made an enormous contribution over more than five decades. Through his mentoring, guidance and friendship, he helped launch the careers of countless international scientists over multiple (both academic and actual) generations. In the context of (mostly) small-angle scattering, I will offer here my personal reflections on John’s contributions to my own career trajectory which began as his PhD student more than (and quite astonishingly) 30 years ago.
In 2004 I was a postdoc in John’s group in Canberra and was tasked with supporting him in his role as an expert witness in a patent dispute.
The dispute hinged on the technical meaning of “emulsion” and whether the allegedly infringing product was an emulsion. John spoke of this work a number of times over the years, but here I will discuss in a bit more detail how we tackled this question, what it taught me, and show some results from experiments inspired by this case.
Exchanging ideas is an important driving force for science and development. The health and environmental needs for clean water are evident but the availability is often challenging. The seeds of Moringa oleifera have been used to flocculate impurities but are primarily exploited on a village scale. Understanding how this process works has provided for a range of scattering, reflection, and diffraction experiments to complement other studies. Apart from assisting the development of water treatment, a number of basic insights into adsorption, floc structure and interaction with various pollutants emerge.
I will briefly tell the long adventure with John, starting with pin-echo "puzzle" on SDS in 191, then building several versions of the Huxley-Holmes at RSC in Canberra near John's office, and later crossing paths with John on always puzzling questions till the extraordinary Lecture John gave over video transmission for the fifty years of D11.
In the early seventies, John White’s application of inelastic neutron scattering to study dynamics of amphiphiles and macromolecules in solution [1] laid the ground work for studies of biological molecular dynamics by neutron scattering, studies that are still very much of current interest half a century on [2].
[1] John William White, Neutron diffraction, inelastic scattering and the structure of amphiphiles and macromolecules in solution, PROCEEDINGS OF THE ROYAL SOCIETY A, 27 August 1975 https://doi.org/10.1098/rspa.1975.0129.
[2] Giuseppe Zaccai, Molecular dynamics in cells: A neutron view, BBA - General Subjects 1864 (2020) 129475.
The physical chemist H.W."Tommy" Thompson became a fellow and chemistry tutor at St John's College, Oxford (SJC) in the 1930s after studying in Germany with Fritz Haber and Max Planck. He pioneered studies with infrared spectroscopy, notably realising that vibrational spectra were useful identifying fingerprints for molecules. His students at SJC continued diversifying these activities. One, Rex Richards, developed nuclear magnetic resonance as a chemical tool. John White obtained a scholarship to study in Oxford, and joined Richard's group. His doctorate project was the measurement of diffusive motions by using the coupling of e.s.r. excitations to stimulate n.m.r. transitions (the Overhauser effect). Two instruments with e.s.r. in the X-band and Q-band frequency ranges allowed observation of relaxation on two different time scales. (One of John's own students, John Collingwood, later built a low magnetic field instrument that offered a third timescale.) In 1963 Tommy was increasingly busy with the Royal Society, and the Football Association (chair 1976-81), and John was appointed to a fellowship at SJC to assist in teaching chemistry to undergraduates, including myself. Tommy engaged Peter Day the following year to teach inorganic chemistry at SJC. Students of John at SJC joined in his research activities. Some who continued with neutron spectroscopy include Andrew Taylor, and Frans Trouw, Philip Reynolds and Andrew Harrison. R.K "Bob" Thomas was initially one of Tommy's students, and took over John's group when he came to the ILL.
In 1963, Roger Elliot, the SJC physics tutor, invited Peter Egelstaff to dine at the college. Peter was head of the Pile Neutron Research Group at Harwell, with strong interests in liquid properties (water, liquid sodium, etc. for moderators). John was invited to use the time of flight (ToF) instruments at Harwell, resulting in the paper with Julia (Stretton Downes) Higgins and Peter on beta-quinol clathrates where the vibrations of the guest molecules could be distinguished from the host by selective deuteration. The success of these measurements led to a wide range of experiments using deuterium substitution to emphasize molecular motions from selected parts of systems. Rotational diffusion in small molecules (e.g. methanol) too was a subject for ToF measurements. Having observed the vibrational spectra of the crystalline hosts in the clathrate experiments, John embarked on projects to measure phonons in molecular crystals, which could lead to a better understanding of intra-molecular forces in solids. Systems studied included urea, and aromatics like naphthalene and p-dichloro-benzene. For the latter two Stuart Pawley offered his phonon calculation program, which was specific to crystal structures of this symmetry. Inelastic neutron measurements followed and prompted improvements to the simple models initially proposed which were originally intended to improve accuracy in crystallographic studies. Both ToF and triple-axis spectrometers were used. Later Philip Reynolds benefited greatly from visits to Risø where Jørgen Kjems took an active interest and generously gave instrument time. Further experiments extended to crystalline polymers (polyethylene, poly-oxy-methylene). Diffusion in restricted environments was examined in experiments with water in Montmorillonite clay layers. The inter platelet spacing can be varied by changing the concentration of ions in the aqueous solution. The gaseous state was not ignored either. The dynamics of adsorbed gases first on fumed silica, then Graphon could be assessed. As with many experiments started at Harwell the later availability of high-resolution measurements at the ILL could be analysed in more detail over greater ranges. Other intercalate experiments looked at hydrogen and methane in caesium/graphite supports. New results from proton tunnelling showed the sensitivity of the technique to examine effects of the local environment on the dynamics.
John's interest in resonance experiments continued with John Hayter and Graham Jenkins using polarised neutrons at Harwell to examine the potential for modifying diffraction patterns by flipping proton spins selectively, as in ENDOR measurements. When John came to the ILL he brought Graham Jenkins to work with Peter Seifert on the dynamic spin polarisation filter IN9.
I will try and present a few topics from these wide ranging experiments.
His later works after returning to the ANU in Australia were mostly in the fields of small-angle scattering and neutron reflectivity using the Opal reactor at Lucas Heights.
Industry needs new natural ingredients – there is a lack of knowledge of the fundamentals of controlling lipolysis in complex matrices. Based on neutron and x-ray data we will show the nature of the oil/water-interphase and how the processes that can occur during lipolysis can change the structure and composition in the interfacial layer. We will discuss how triglycerides can orient at the interface and lead to uptake of water [1]. Neutron reflectivity shows that the internal structure is very complex after lipolysis. Modelling suggests a highly disorganised, stratified structure that depends on the pH. Based on these experiments we will discuss the modification of edible oils from plant raw materials. Such information can be used to predict stability of food formulations and can serve as a tool to design and build up new and more complex matrices. We show that a new thick creamy emulsion based on oat oil can be created without additives with green biobased tools. X-ray data show that this is due to the structural change in the oil. The conditions of the dispersing solution can be used to tune the final emulsion properties. The study is part of an ongoing project aimed at obtaining more sustainably produced food ingredients that needs less additives and energy. In the long term new healthy products can be developed as e.g., carriers for bioactive food ingredients.
References:
[1] B. A. Humphreys, J. Campos-Terán, T. Arnold, L. Baunsgaard, J. Vind, C. Dicko, T. Nylander, The influence of pH on the lipase digestion of nanosized triolein, diolein and monoolein films. Front. Soft Matter 2022, 2, 929104.
Acknowledgements:
We are grateful for the financial support from Swedish Research Council (2018–05013) as well as The Swedish Agency for Economic and Regional Growth (20307448) through the European Union Regional Fund and the Skane Region. The valuable discussions and input from José Campos-Terán, Thomas Arnold, Lone Baunsgaard,Jesper Vind, Max Skoda, Philipp Gutfreund and Cedric Dicko are gratefully acknowledged.
The eponymous use of white neutron and X-ray radiations by John White has been pursued in various ways, at the interface of chemistry, physics and engineering. John had a dynamic yet gentle and profound influence on several developments of related prototype hard radiation instrumentations and their phase space philosophies, that spanned both major facilities and tabletop equipment. Some timely and significant advances in those contexts during the last three decades will be expressed from the perspective of one of his many former chemical physics students.
John White played an important role at Argonne National Laboratory when the Intense Pulsed Neutron Source (IPNS) started to operate in the early 1980s. At that time neutron scattering in the US was dominated by physicists, and, as a chemist, John, appointed as a Laboratory Fellow in 1984, was able to talk to many senior scientists at the Laboratory, including the Director, and convince them of the importance of neutrons for a wide range of applications in both chemistry, soft matter, and biology. He strongly advocated building a small-angle scattering machine, a reflectometer, and an inelastic scattering spectrometer to broaden the appeal of neutron scattering across other disciplines, in addition to condensed-matter physics, and we successfully accomplished this goal. John went on to be involved in science, together with ANL collaborators, from all three machines. At that time IPNS was faced with closure in the mid-1980s due to budgetary pressure, but its success across a range of disciplines allowed it to escape this fate, and run until 2008. John's advocacy was a key ingredient in this success.