New research shows how a laser technique reveals the way the sun's energy moves inside plants, unravelling some of the inner workings of this efficient solar energy process.
The research, published in Physical Review Letters, explains how the team, led by Dr Ian Mercer from the School of Physics at University College Dublin, who is a visiting researcher at Imperial College London, used a laser to probe a sample of a protein found in bacteria, called LH2, which was provided by the University of Glasgow. This bacterial protein was used because it harvests light in the same way as photosynthetic plant proteins. By illuminating the sample with a combination of high power laser pulses all derived from the same laser, the researchers obtained a map of bright spots on a camera in a tiny fraction of a second. The position of each spot corresponds to a unique angle of light emitted from the sample and this directly relates to how electrons in the protein respond to the laser light and to each other.
Alternative laser-based techniques for gathering such information do already exist, but require the sample to be exposed to the laser light for a long period, which may lead to sample degradation. They also require much more intensive computer processing.
The researchers needed a very powerful and stable laser in order to get the new approach to work efficiently and accurately. They used the Astra laser at the Science and Technology Facilities Council's Rutherford Appleton Laboratory (RAL).
With this laser, a map can be captured with a single pulse of laser light meaning that full information can be gathered prior to, or during, a chemical reaction. The technique can also be used to characterise high-value, delicate samples because only a small quantity of sample is required. And with one thousand laser pulses available per second from the laser, there is potential for rapid automated sample characterisation.