Physical Sciences Colloquia
The Physical Sciences Colloquia are intended for a broad audience – from undergraduate students to retired professors. The topics encompass the interests of all research groups in the School: from Applied Optics, through Astrophysics, Planetary Science and Forensic Imaging to Functional Materials Physics and Chemistry.
The colloquia are held on Wednesdays at 2 pm in the Ingram Lecture Theatre (ILT) unless otherwise specified. The programme is constantly updated. Click on the speaker’s name and the talk’s title for biographical information/contact details and an abstract, respectively.
All our colloquia for this term will be on our Events Calendar which we regularly update when we have a confirmed speaker so make sure to check back regularly! You can also have a look at speakers for our present term by clicking on their entry below:
30th May 2018 – Dr Elizabeth Hillard (Centre de Recherche Paul Pascal – CNRS, Bordeaux)
16th May 2018 – Prof. Dudley Shallcross (Department of Chemistry, University of Bristol) – RSC Nyholm Lecture
9th May 2018 – Prof. Lewis Dartnell (Department of Life Sciences, University of Westminster)
28th March 2018 – Dr Tim Easun (Department of Chemistry, Cardiff University)
Dynamic behaviour in metal-organic frameworks
The primary applications of metal-organic frameworks (MOFs) are often proposed to be in gas storage and separation, and they are indeed highly promising crystalline microporous materials with potential to act as rapid uptake/release sorbents for important gases such as CO2, H2 and CH4. However, increasingly the more niche, specialised properties and functions of well-designed MOFs are gaining traction. A crucial aspect of any advanced study on MOFs is the use of a wide variety of analytical techniques to study the behaviour of both the frameworks and their guests. This talk will briefly describe examples of some of these techniques, including synchrotron-based experiments, and specifically highlight the area of photoresponsive MOFs, describing examples of the different strategies to incorporate and perhaps exploit light-induced structural changes in framework materials.
7th March 2018 – Ashley George CC FRSC (Global Head of Innovation & Consumerisation CoE, GSK)
28th Feb 2018 – Dr Karen Robertson, Max Planck Institute for Colloids and Interfaces
Crystal Flow: understanding and controlling crystalline materials; 2pm, Ingram Lecture Theatre, Ingram Building, Canterbury Campus
Crystals are used in a vast range of applications, including pharmaceuticals, smartphones and insulation, where efficiency is often related to the crystal structure. For example, when a more stable crystalline form of the HIV/AIDs drug, Ritonavir, began to appear in factories, the original and more soluble (directly related to how well it is taken up into the body) crystalline form could not be produced. This meant that it had to be removed from the market whilst a new formulation was devised.
Crystallising in flow environments can allow for control over the resultant material not achievable in standard methods.1 Flow crystallisation has seen a surge of innovation in the past five years with a range of research lab-accessible milli-scale crystallisers developed.2,3 Employing varied flow crystallisers we have accessed a range of crystal attributes such as crystalline form (polymorph), particle size and shape control.4,5
The next evolutionary step in crystallisation control has been realised in the adaptation of a bespoke liquid-segmented crystalliser (KRAIC) for in-situ X-Ray analysis on the high resolution powder beamline (I11) at Diamond Light Source. The on-line structural information gained from this platform can help us to understand the crystallisation process as it is happening and therefore design more efficient routes to more efficacious materials.
1. K. Robertson, Chemistry Central Journal, 2017, 11:4
2. A. J. Alvarez, A. S. Myerson, Crystal Growth and Design, 2010, 10, 2219-2228
3. R. J. P. Eder, S. Schrank, M. O. Besenhard, E. Roblegg, H. Gruber-Woelfler, J. G. Khinast, Crystal Growth and Design, 2012, 12, 4733-4738
4. K. Robertson, A. R. Klapwijk, P.-B. Flandrin, C. C. Wilson, Crystal Growth and Design, 2016, 14, 4759-4764
5. K. Robertson,* P.-B. Flandrin, H. J. Shepherd, C. C. Wilson, Chemistry Today, 2017, 35 (1), 19-22
7th Feb 2018 – Prof Anna Peacock, Optoelectronics Research Center (ORC), University of Southampton
Semiconductor Optical Fibres: A New Platform for Nonlinear Optics?; 2pm, Ingram Lecture Theatre, Ingram Building, Canterbury Campus
Combined OSA Student Chapter Talk/SPS Colloquium
Silicon photonics is currently one of the largest growing areas of research, attracting considerable interest amongst both academic and industrial communities. The ability to incorporate the semiconductor functionality into the optical fibre geometry provides an important step towards the seamless integration of these two technologies, as well as opening up new application areas for optical fibre systems. This seminar will review recent progress in the emerging field of semiconductor optical fibres, highlighting the different materials and novel geometries that are available through this platform. Particular focus will be placed on our effort to characterize the nonlinear optical properties of the silicon core fibres from telecoms wavelengths up to the short-wave infrared, with the results being discussed in relation to future device development.
31st Jan 2018 – Prof Andrew G. Green, London Centre for Nanotechnology
Path integrals over entangled states; 2pm, Ingram Lecture Theatre, Ingram Building, Canterbury Campus
Entanglement is fundamental to quantum mechanics. It is central to the EPR paradox and Bell’s inequality, and gives robust criteria to compress the description of quantum states. In contrast, the Feynman path integral shows that quantum transition amplitudes can be calculated by summing sequences of states that are not entangled at all. This gives a clear picture of the emergence of classical physics through the constructive interference between such sequences. Accounting for entanglement is trickier and requires perturbative and non-perturbative expansions.
We combine these two powerful and complementary insights by constructing Feynman path integrals over sequences of states with a bounded degree of entanglement. I will discuss the physical insights that such a construction affords.
17th Jan 2018 – Dr. Malte Grosche, Cavendish Laboratory, University of Cambridge
Correlated States Near Pressure-Induced Instabilities; 2pm, Ingram Lecture Theatre, Ingram Building, Canterbury Campus
Many complex materials display an interesting interplay between structural and electronic instabilities, which can be studied effectively under applied pressure. If a continuous structural phase transition is suppressed to low temperatures, as in the quasi-skutterudite system (Sr/Ca)3(Ir/Rh)4Sn13 , low-energy vibrational excitations can arise that boost superconductivity and cause a linearly temperature dependent electrical resistivity. We report that the aperiodic high-pressure host-guest structure of elemental bismuth displays a similar phenomenology, suggesting significantly enhanced phonon spectral weight at low energies.
It is increasingly desirable to probe the electronic structure near pressure-induced quantum phase transitions directly and in detail. We have observed the electronic Fermi surface on the metallic side of a Mott insulating transition by high pressure quantum oscillation measurements in NiS2 . Our results show that the Fermi surface remains large on approaching the Mott insulating state, consistent with Luttinger’s theorem, whereas the quasiparticle effective mass is strongly renormalised.
1. Goh et al. Phys. Rev. Lett. 114, 097002 (2015) 2. Friedemann et al. Sci. Rep. 6, 416 (2016)
Past speakers are on the next page.