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Dr David R Worrall
Senior Lecturer in Physical Chemistry
BSc CNAA PhD Loughborough CChem FRSC
Telephone: 01509 222567
E-mail: D.R.Worrall@lboro.ac.uk
Kinetics of elementary reactions at interfaces: Nanosecond time
resolved diffuse reflectance laser flash photolysis is being used to study
a variety of uni- and bimolecular processes on the surfaces of both silica
gel and microcrystalline celulose. The processes studied include triplet-triplet
annihilation, triplet-triplet energy transfer and electron transfer between
cation radicals of anthracene and a number of electron donors. Kinetic
models are also being developed to describe these processes in terms of
fractal- and two-dimensional rate constants, and also in terms of a dispersive
kinetic model assuming a distribution of rate coefficients. Monte-Carlo
simulations are used to correlate fitted parameters with physical models
of the behaviour of molecules on surfaces.
Non-linear optical phenomena: The phenomenon of reverse saturable
absorption is an area of active study, along with the development of computer
simulations of the processes involved. Novel bimolecular systems are under
development to add greater flexibility to the protected wavelength envelope.
Photochemistry in supercritical fluids: Triplet-triplet energy
transfer and photoinduced electron transfer are being used to study diffusional
characteristics and clustering effects in modified supercritical fluid
carbon dioxide. Supercritical fluid Xenon is being investigated as a medium
in which to study excited triplet state reactions since we have demonstrated
that intersystem crossing yields are significantly enhanced in this fluid
relative to organic solvents. The generation and subsequent fate of singlet
molecular oxygen in supercritical fluids is currently being studied, with
models based on radial distribution functions being applied to explain
the observed kinetics.
Selected Publications
Sikorski, M., Prukala, D., Insinska-Rak, M., Khmelinskii, I.V., Worrall, D.R., Williams, S.L., Hernando, J., Bourdelande, J.L., Koput, J. and Sikorska, E. "Spectroscopy and photophysics of dimethyl-substituted alloxazines" Journal of Photochemistry and Photobiology A:Chemistry, 200(2-3), 2008, 148-160.
Worrall, D.R. and Abdel-Shafi, A.A. “Photosensitized production
of singlet oxygen and factors governing its decay in xenon and carbon
dioxide supercritical fluids” Journal of Photochemistry and
Photobiology A:Chemistry 186, 2007, 263-269.
Worrall, D.R., Williams, S.L. and Ganguly, T. “Ion-electron recombination
on silica gel surfaces: experiment and modelling” Photochemical
and Photobiological Sciences 5(9), 2006, 844-849
Sikorska, E., Khmelinskii, I.V., Kubicki, M., Prukala, W., Hoffmann, M.,
Machado, I.F., Ferreira, L.F.V., Karolczak, J., Worrall, D.R., Krawczyk,
A., Insinska-Rak, M. and Sikorski, M. “In search of excited state
proton transfer in lumichrome dimer in solid state: theoretical and experimental
approach” Journal of Physical Chemistry A 110(14), 2006,
4638-4648
Insinska-Rak, M., Sikorska, E., Bourdelande, J.L., Khmelinskii, I.V.,
Prukala, W., Dobeke, K., Karolczake, J., Machado, I.F., Ferreira, L.F.V.,
Komasa, A., Worrall, D.R. and Sikorski, M. “Spectroscopy and photophysics
of flavin-related compounds: 5-deaza-riboflavin” Journal of
Molecular Structure 783(1-3), 2006, 184-190
Abdel-Shafi, A.A. and Worrall, D.R. “Mechanism of the excited singlet
and triplet states quenching by molecular oxygen in acetonitrile”
Journal of Photochemistry and Photobiology A:Chemistry 172(2),
2005, 170-179
Worrall, D.R., Kirkpatrick, I. and Williams, S.L. “Bimolecular processes
on silica gel surfaces: Energetic factors in determining electron transfer
rates” Photochemical and Photobiological Sciences 3, 2004,
63-70
Worrall, D.R. and Williams, S.L. “Lasers in Chemistry and Engineering:
Diffuse Reflectance Laser Flash Photolysis” Encyclopedia of
Modern Optics, edited by Robert D. Guenther, Duncan G. Steel and
Leopold Bayvel, Elsevier, Oxford, 2004, 31-37
Sikorska, E., Khmelinskii, I.V., Prukala, W., Williams, S.L., Patel, M.,
Worrall, D.R., Bourdelande, J.L., Koput, J. and Sikorski, M. “Spectroscopy
and Photophysics of Lumiflavins and Lumichromes” Journal of
Physical Chemistry 108, 2004, 1501-1508
Abdel-Shafi, A.A., Worrall, D.R and Ershov, A.Y. “Photosensitized
Generation of Singlet Oxygen from Ruthenium(II) and Osmium(II) bipyridyl
Complexes” Journal of the Chemical Society Dalton Transactions
1, 2004, 30-36
Worrall, D.R.; Williams, S.L.; Eremenko, A.; Smirnova, N.; Yakimenko,
O. and Starukh, G. “Laser flash photolysis study of electron transfer
processes of adsorbed anthracene on photocatalytic titania-silica surfaces”
Colloids and Surfaces A: Physicochemical Aspects 230(1-3), 2004,
45-55
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