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Professor David Richards

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Telephone: +44 020 7848 2753

Emaildavid.r.richards@kcl.ac.uk

Office: S6.18

Office Hours

Research Group: Photonics & Nanotechnology Group

Biography

David Richards is a professor of physics and Vice Dean (Research) in the Faculty of Natural & Mathematical Sciences in King’s College London.

He holds MA and PhD degrees in physics from the University of Cambridge and is a Fellow of the Institute of Physics and Fellow of the Royal Microscopical Society. Before moving to King’s College London in 2000, he worked as a research fellow in the Cavendish Laboratory, Cambridge, where he held fellowships from St. John’s College Cambridge and Lloyds’s of London Tercentenary Foundation, before a Royal Society University Research Fellowship. He was the Head of The Physics Department at King’s from 2007-2015. From 2013-15 he was Chair of the UK Standing Conference of Physics Professors (now known as the Heads of Physics Forum).

Research

His past research brings extensive experience in optical spectroscopy and imaging, particularly fluorescence and Raman scattering, and has been concerned with two main themes:

(1)    Until 2010, the study of the electronic and optical properties of semiconductor nanostructures, in particular providing insight through Raman spectroscopy to the properties of plasmons and spin excitations in low-dimensional electron gases.

(2)    Since 1995, Nano- and Bio-photonics.

Research in nanophotonics has included the development, theory and application of scanning near-field optical microscopy, including important contributions to the development of 'tip-enhanced' Raman and fluorescence microscopy. This led to a focus on SERS and the manipulation of fluorescence using plasmonic nanostructures.

He founded the King’s College Centre for Biophotonics, bringing together a strong network of researchers in optical cell and tissue imaging across the university. Research in this area has included the application of nanoplasmonic materials n fluorescence imaging for novel cellular screening assays and the development of ultra-broadband coherent anti-Stokes Raman scattering (CARS) imaging.

He was also a co-founder of start-up Genapta Ltd, which developed a microfluidic fluorescence assay system for drug discovery; Genapta was successfully sold in a trade-sale in 2007/8.

Present Research

Our research is concerned with the development of new optical imaging techniques, with a particular focus on biological application, and on understanding and manipulating photophysical phenomena at the nanoscale. Our research programme falls into two main strands, outlined below. We enjoy strong collaboration with the National Physical Laboratory .

1. Coherent anti-Stokes Raman scattering (CARS) imaging

Coherent Anti-Stokes Raman Scattering (CARS) is a third order non-linear optical process where three input fields coherently generate a fourth.  The amplitude and phase of the generated field depends on molecular vibrational resonances, so the technique can give information on what chemical species are present in a given sample.  In recent years this has found application in biological microscopy, allowing images to be taken using the endogenous (i.e. label-free) vibrational contrast. 

We have recently developed a new implementation of CARS which delivers in a passive all- optical manner the same powerful chemical signature provided by conventional Raman spectroscopy, but orders of magnitude faster, making it possible to explore a wide range of systems (from biological cells to reacting gas flows) in much greater spatial and temporal detail. Signals are free of the non-resonant background signal which has traditionally plagued CARS, while still providing the signal amplification and inherent optical sectioning of multiphoton coherent Raman techniques. We are now developing further this new technique of Spectral Interferometric Polarized Coherent Anti-Stokes Raman Scattering (SIP-CARS), and applying it to biological cell imaging and tissue diagnostics.

2. Plasmonics

We are members of the Reactive Plasmonics (RPLAS) EPSRC Programme. Please see Professor Anatoly Zayats and the RPLAS web-site http://www.reactiveplasmonics.org/

Selection of Publications

Publications Repository

  • F. M. Huang, F. Festy, and D. Richards, Appl. Phys. Lett. 87, 183101 (2005). Tip-enhanced fluorescence imaging of quantum dots.
  • A. L. Demming, F. Festy, and D. Richards, J. Chem. Phys. 122, 184716 (2005). Plasmon resonances on metal tips: Understanding tip-enhanced Raman scattering.
  • F. Perez, C. Aku-Leh, D. Richards, B. Jusserand, L. Smith, D. Wolverson and G. Karczewski, Phys. Rev. Lett. 99, 026403 (2007), From spin flip excitations to the spin susceptibility enhancement of a two dimensional electron gas.
  • T. Ritman-Meer, N. Cade and D. Richards, Appl. Phys. Lett. 91, 123122 (2007), Spatial imaging of modifications to fluorescence lifetime and intensity by individual Ag nanoparticles.
  • N.I. Cade, T. Ritman-Meer, K. Kwakwa, D. Richards, Nanotechnology 20, 285201(2009), Plasmonic engineering of metal nanoparticles for enhanced fluorescence and Raman scattering.
  • N.I. Cade, T. Ritman-Meer, D. Richards, Phys. Rev. B 79, 241404(R) (2009), Strong coupling of localized plasmons and molecular excitons in nanostructured silver films.
  • N.I. Cade, G. Fruhwirth, S.J. Archibald, T. Ng, and D. Richards, Biophys. J 98 in press (2010), A cellular screening assay using analysis of metal-modified fluorescence lifetime.
PhD Vacancies

Applications are invited for research in theExperimental Biophysics & Nanotechnology group.

To apply for the Physics MPhil/PhD  please fill in an application form  Further details and guidelines can be found here.

All relevant information regarding eligibility, including academic and English language requirements, is available from the online prospectus.

Current Project Descriptions

Broadband Spectral Interferometric Polarized Coherent Anti-Stokes Raman Scattering – a non-linear optical approach to fast all-optical chemical fingerprinting

Coherent Anti-Stokes Raman Scattering (CARS) is a third order non-linear optical process where three input fields coherently generate a fourth. The amplitude and phase of the generated field depends on molecular vibrational resonances, so the technique can give information on what chemical species are present in a given sample. In recent years this has found increasing application in biological microscopy, allowing images to be taken using the endogenous (i.e. label-free) vibrational contrast. We have recently developed a new implementation of CARS which delivers in a passive all- optical manner the same powerful chemical signature provided by conventional Raman spectroscopy, but orders of magnitude faster, making it possible to explore a wide range of systems in much greater spatial and temporal detail. In Spectral Interferometric Polarized Coherent Anti-Stokes Raman Scattering (SIP-CARS), signals are free of the non-resonant background signal which has traditionally plagued CARS, while still providing the signal amplification and inherent optical sectioning of multi-photon coherent Raman techniques.

This project is concerned with deriving a full understanding of the underlying physics of the SIP-CARS technique, allowing significant further enhancement of its capability. Experimental measurements will be complemented by theoretical and computational analysis of the optical four-wave mixing process within the focal volume. Computational approaches for the recovery of resonant response from CARS spectra will also be applied, to enable a detailed comparison with SIP-CARS and analysis of different contributions to the CARS signal. In SIP-CARS the real signal components (including the non-resonant background signal) cancel in a balanced homodyne detection scheme, leaving only the imaginary resonant components; the project will also explore opportunities for additional signal amplification, and involve the study of noise and its impact on hyperspectral cluster analysis, and the study of processes that break the symmetry of the balanced detection scheme (such as in polarisation-dependent media), mixing a portion of the real components into the spectrum.

This project offers the opportunity to bring together experiment with theoretical and computational analysis, and to develop skills in the development and trouble-shooting of a complex ultrafast optical experimental system. The successful candidate should be a problem-solver with a good understanding of optical physics, and strong experimental, theoretical and programming skills.

 

Quantitative broadband coherent anti-Stokes Raman scattering (CARS) imaging for the study of in vivo lipid metabolism in the nematode C.elegans

David Richards, Department of Physics
Stephen Sturzenbaum, Faculty of Life Sciences and Medicine

Coherent Anti-Stokes Raman Scattering (CARS) is a third order non-linear optical process where three input fields coherently generate a fourth. The amplitude and phase of the generated field depends on molecular vibrational resonances, so the technique can give information on what chemical species are present in a given sample. In recent years this has found increasing application in biological microscopy, allowing images to be taken using the endogenous (i.e. label-free) vibrational contrast. We have recently developed a new implementation of CARS which delivers in a passive all- optical manner the same powerful chemical signature provided by conventional Raman spectroscopy, but orders of magnitude faster, making it possible to explore a wide range of systems in much greater spatial and temporal detail. In Spectral Interferometric Polarized Coherent Anti-Stokes Raman Scattering (SIP-CARS), signals are free of the non-resonant background signal which has traditionally plagued CARS, while still providing the signal amplification and inherent optical sectioning of multiphoton coherent Raman techniques.

The development and application of SIP-CARS, has facilitated the 2- and 3-dimensional in vivo imaging of the microscopic model nematode (Caenorhabditis elegans). In “proof of principle” experiments, this technique has not only enabled the identification of differences in lipid saturation distributions in C. elegans but demonstrated that the technique is sufficiently sensitive to detect the effects of lipid metabolism altering drugs on C. elegans. This project will further optimize the application of SIP-CARS to define the modified fat status in stains harbouring mutations in genes known to be implicated in fat metabolism (e.g. fat-5, daf-2, sbp-1 etc.) as well as novel targets identified in our laboratory by means of global transcriptomics (e.g. F19H6.6, B034832, C40A11.8 etc.). Given that mutants are not available for the novel targets, gene knockdowns (rather than knockouts) will be generated via RNA interference (RNAi). Taken together, the application of SIP-CARS within the context of an established model organism will allow us to pinpoint evolutionary conserved genes which are instrumental in obesity and diseases linked to impaired fat metabolism.

The PhD student will be fully integrated into both the Experimental Biophysics & Nanotechnology Research Group of the Department of Physics, and the Toxicogenomics Research Group within the Faculty of Life Sciences and Medicine at King’s. The successful candidate should have a good understanding of optical physics, strong experimental and programming skills, and a desire to cross disciplines and develop new skills in biological science.

 For further details contact Professor David Richards.

 

Photonics & Nanotechnology Group
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