Professor Nigel Mason
Professor Nigel Mason OBE is a Professor of Molecular Physics and Head of the School of Physical Sciences.
Professor Mason began his research career by exploring the simultaneous absorption of energy from photons and electrons to excite an atom, a process akin to two photon absorption and predicted theoretically in the 1930s but not previously demonstrated experimentally until Nigel's PhD studies and early postdoctoral studies (1984-87) in the Department of Physics and Astronomy, University College London (UCL). This work led to his being awarded a Royal Society University Research Fellowship (1990-1998), which allowed him to form the Molecular Physics Group at UCL.
The discovery of the ozone hole and global warming, with the subsequent need to understand spectroscopy and reaction dynamics in terrestrial stratosphere, led to Nigel's development in physical chemistry/chemical physics and his first experiments on ice surfaces, since it was determined that such surface chemistry played a key role in polar stratospheric vortex leading to ozone depletion. He went on to study ice on planetary surfaces and on dust grains in the interstellar medium and thus became an ‘astrochemist and planetary scientist’.
Nigel's work in this area was a contributing factor in his joining the Open University in 2002/3, where he interacted with the internationally acclaimed Planetary Science group led by the late Colin Pillinger. He was involved in the founding of the OU Astrochemistry group while continuing electron and surface studies (with a focus on nanolithography) in the Atomic, Molecular and Plasma Physics group. A new field of research developed in the study of irradiation of biomolecular systems including DNA, with initial applications to astrobiology and, more recently, in the development of next-generation radiotherapy using ion beams and nanoparticles as radiosensitisers.
His research has led Nigel to leadership roles in many national and international research programmes and he is currently Chair of Europlanet, Europe’s largest forum for planetary sciences, which will become a membership Society in 2018-19. He is also on the steering committee for the forthcoming European Astrobiology Institute (EAI) and a member of European astrochemistry, radiation chemistry and nanolithography networks and programmes. Outside Europe, he has close links with the emerging space community in India and electron physics communities around the world; he chairs the ‘Dissociative Electron Attachment – DEA club’. He also chairs The Sir John Mason Academic Trust, a small family trust established in honour of his father, a distinguished scientist and pioneer of the study of cloud physics.
Professor Mason's research may be broadly classified as ‘molecular physics’, which encompasses several interdisciplinary themes:
- astrophysics and astrochemistry
- environmental and atmospheric physics
- plasma physics and nanolithography
- next-generation radiotherapy.
However, all of this research is centred upon fundamental studies exploring electron- and photon-induced fragmentation of molecules and the study of the subsequent reactivity that such processes may induce in local media. Nigel has over 350 refereed publications with h-index of >30.
Bockova, J. et al. (2019). Mapping the complex metastable fragmentation pathways of excited 3-aminophenol+. International Journal of Mass Spectrometry [Online] 442:95-101. Available at: https://doi.org/10.1016/j.ijms.2019.05.006.This work applies the technique of mapping ion detection using a reflectron mass spectrometer against flight-time and reflection voltage to elucidate the complex metastable fragmentation pattern of the biomolecular ion 3-aminophenol+ (3-AP+, C6H7NO+). Multi-photon ionization experiments revealed the excited ion's fragmentation routes for the first time and comparisons with calculated flight-times enabled 18 â¯different Î¼s-timescale dissociations to be assigned. These included the rare observation of a double hydrogen loss channel from a fragment ion. DFT calculations provided further insights into the most prominent apparent fragmentation sequence: 3-AP+ (m/z 109) â HCO + C5H6N+ (m/z 80) â CNH + C4H5+ (m/z 53) â C2H2 + C2H3+ (m/z 27).
Pavithraa, S. et al. (2019). Identification of a unique VUV photoabsorption band of carbonic acid for its identification in radiation and thermally processed water-carbon dioxide ices. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy [Online] 215:130-132. Available at: https://doi.org/10.1016/j.saa.2019.02.037.Carbonic acid was synthesized within an ice containing water and carbon dioxide by irradiation of ~9â¯eV photons. Vacuum UltraViolet (VUV)/UltraViolet (UV) photoabsorption spectra of the irradiated ice revealed absorption features from carbon dioxide, ozone, water, carbon monoxide and oxygen in addition to a band peaking at ~200â¯nm which is identified to be characteristic of carbonic acid. After thermal processing of the irradiated ice leading to desorption of the lower volatile ices, a pure carbonic acid spectrum is identified starting from 170â¯K until sublimation above 230â¯K. Therefore the ~200â¯nm band in the VUV region corresponding to carbonic acid is proposed to be a unique identifier in mixed ices, rich in water and carbon dioxide typically encountered on planetary and satellite surfaces.
Gope, K. et al. (2019). DEA dynamics of chlorine dioxide probed by velocity slice imaging. Physical Chemistry Chemical Physics [Online]. Available at: https://doi.org/10.1039/C8CP06660.We report, for the first time, the detailed dynamics of dissociative electron attachment to the atmospherically important chlorine dioxide (OClO) molecule exploring all the product anion channels. Below 2 eV, the production of vibrationally excited OCl? dominates the DEA process whereas at electron energies greater than 2 eV, three-body dissociation is found to result in O? and Cl? production. We find that the internal energy of OCl? and the kinetic energy of Cl? are large enough for them to be relevant in the ozone-depleting catalytic cycle and more investigations on the reaction of these anions with ozone are necessary to completely understand the role of DEA to OClO in ozone depletion. These results also point to an urgent need for comprehensive theoretical calculations of the DEA process to this atmospherically important molecule.