Faculty of Science School of Chemistry

Toby Bell

Faculty of Science Centenary Research Fellow

CONTACT DETAILS:

Address: Bio21 Institute, School of Chemistry, University of Melbourne, Parkville, VIC 3010 Australia

Room: Bio21 Inst., 285

Email: tbell@unimelb.edu.au

Field of expertise

Single Molecule Spectroscopy

Single molecule spectroscopic techniques are capable of probing matter at the ultimate resolution limit – one molecule at a time. The main advantage in studying single molecules is that information concerning the distribution of a given parameter rather than just an average value for it can be obtained. Single molecule techniques can also reveal rare events and phenomena that are concealed by ensemble averaging in bulk experiments. We are using single molecule spectroscopic techniques to investigate the fundamental photophysics of single molecules in the following areas.
  • Excited state annihilation processes: Compounds capable of delivering photons on demand are of interest in quantum cryptographic and quantum computing applications. Excited state annihilation is one mechanism by which so-called deterministic single photon emission can be achieved from fluorescent compounds.[1-3] We are studying annihilation phenomena in multi-chromophoric molecular systems such as short single polymer chains of few (~3-10) repeat units and multi-chromophoric dendrimer molecules.
  • Electron transfer: This is not easy to study in single molecules due to it usually quenching the fluorescence to undetectable levels.[4] One way around this limitation is via an emissive charge separated state.[5] We are studying electron transfer in single naphthalene diimide based molecules that have a high (>0.5) fluorescence quantum yield. In particular, we wish to determine the cause(s) of long time scale fluorescence intermittencies in these systems.[6]
  • FRET (Frster resonance energy transfer): FRET between fluorescent labels is a powerful tool for probing the dynamics of large molecular structures. We are studying FRET in fluorescent proteins and labelled peptides in order to learn how to obtain information concerning the dynamics of protein conformational changes and catalytic activity.
Selected Publications:
  1. Masuo, S; Vosch, T.; Cotlet, M.; Tinnefed, P.; Habuchi, S.; Bell, T. D. M.; Oesterling, I.; Beljonne, D; Champagne, B.; Mllen, K.; Sauer, M.; Hofkens, J.; De Schryver, F .C, J. Phys. Chem. B, 2004, 108, 16686-16696.
  2. Bell, T. D. M.; Habuchi, S.; Masuo, S.; Oesterling, I.; Mllen, K.; Tinnefeld, P; Sauer, M; Van der Auweraer, M.; Hofkens, J.; De Schryver, F. C., Aust. J. Chem.,2004, 57, 1168-1173.
  3. Bell, T. D. M.; Jacob, J.; Angeles-Izquierdo, M.; Fron, E.; Nolde. F.; Hofkens, J.; Mllen, K.; De Schryver, F. C., Chem. Commun, 2005, 39, 4973-4975.
  4. Bell, T. D. M.; Stefan, A.; Masuo, S.; Vosch, T.; Lor, M.; Cotlet, M.; Hofkens, J.; Bernhardt, S.; Mllen, K.; Van Der Auweraer, M.; Verhoeven, J. W.; De Schryver, F .C, ChemPhysChem. 2005, 6, 942-948.
  5. Angeles-Izquierdo, M.; Bell, T. D. M.; Habuchi, S.; Fron, E.; Pilot, R.; Vosch, T.; De Fevter, S.; Verhoeven, J.; Jacob, J.; , K, K.; Hofkens, J.; De Schryver, F. C. Chem. Phys. Lett. 2005, 401, 503-508.
  6. Yeow, E. K. L.; Melnikov, S.M.; Bell, T. D. M.; De Schryver, F. C.; Hofkens, J. J. Phys Chem. A, 2006, 110, 1726-1734.

 

 
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