Department of Physics
University of Minho
4710-057 Braga 
PORTUGAL

Study of radiative transfer in optically thick media

 
     Photophysical properties of dye (porphyrins, phthalocianines) films and dye-polymer systems.
      Photoinduced electronic energy and charge transfer processes at dye-semiconductor oxide interfaces.

Key Words:  Electronic energy transfer, charge transfer, semiconductor oxides.

Collaborations:

Centro de Química Estrutural, Instituto Superior Técnico, Lisboa.

Centro de Química-Física Molecular, Instituto Superior Técnico, Lisboa

Laboratoire de Physique des Interfaces et des Couches Minces, École Polytechnique, Palaiseaux, France.

Coordinator: M. Isabel C. Ferreira

 
Research within this area is focused on the study of a wide variety of organised molecular structures and microheterogeneous systems. Microheterogeneous systems can be obtained with self-organising molecules (eg. lipids, surfactants). Photophysical properties of molecular probes can give indication about the local environment.

Key Words:  Molecular organized systems, molecular probes, electronic energy transfer, photoluminescence.

Collaborations:

• Chemistry Department, University of Coimbra.
• Centro de Química Estrutural, Instituto Superior Técnico, Lisboa.
• Centro de Química-Física Molecular, Instituto Superior Técnico, Lisboa.
• Unité Mixte CNRS/BioMérieux, ENS de Lyon, France.

Coordinator: M. Elisabete C. D. R. Oliveira 

 
We have used the optical Kerr effect to induce transverse spatial gradients in the refractive index of “water-in-oil” microemulsions and have recently used intense laser light to induce phase transitions in these liquids. 

Key Words: third-order nonlinear optical susceptibility, diffusion limited dynamics, laser induced phase transitions.

Collaborations:

• Departamento de Química, Universidade de Coimbra.
• Centro de Química Estrutural, Instituto Superior Técnico, Lisboa.
• Grupo de Optoelectrónica, Universidade do Porto.
• Clarendon Laboratory, Oxford University.
• Department of Physics, University of Exceter

Coordinator: Michael Belsley 

The description of radiation trapping in atomic vapours has recently gained a new interest with the development of a multiple scattering representation of the solution of the classical transfer equation.
Past work has been focused on development of a stochastic description of radiative transport in high concentration molecular media that was subsequently proved to be equivalent to the multiple scattering approach originally developed for atomic media. This theory has been tested for the molecular media and we plan to use the same basic theoretical basis to describe the dynamics of radiative transport (time evolution of the intensity and polarization) for neutral atomic vapours.
A stochastic simulation (Monte-Carlo, Markov Chains, Lévy flights) will be conducted for several spectral line profiles (Doppler, Lorentz, Voigt) and particular geometries (finite slab, cylinder and sphere).
These studies are relevant to several important applied areas, including the optimization of organic scintillation counters, luminescent solar concentrators and atomic line filters used in optical information transmission, although the most important commercial application are fluorescent lamps.

• Stochastic Processes
• Kinetics in Confined Media
• Photoluminescence (time-resolved and steady state) 
• Laser Flash Photolysis
• Photoconductivity (transient and steady state)
• Wave mixing/coherent spectroscopy
• Optical Spectroscopies
• Static and Dynamic Light-Scattering