New laser technique reveals actual photosynthesis, frame by frame

February 7th, 2009 - 12:37 pm ICT by IANS  

London, Feb 7 (IANS) Researchers have clicked for the first time, images showing how the sun’s energy moves inside plants - a practical demonstration of photo-synthesis, the most efficient solar energy process on earth.Inside a photosynthetic protein, the sun’s energy is efficiently guided across the molecule to drive a chemical reaction that stores energy as food and takes in carbon dioxide.

However, in very small-scale systems such as photosynthetic molecules, quantum effects come into play making it difficult for scientists to explain how photosynthetic molecules are able to transport energy with remarkably high efficiency.

“These new pictures are instantaneous snap-shots of energy being transported between electrons across a protein. Remarkably, the pictures go further in unravelling the complex way the electrons interact. This gives us something akin to a fingerprint for electronic couplings,” said Ian Mercer from the School of Physics, University College Dublin, co-author of the new study and visiting researcher at Imperial College London.

The researchers probed a sample of a protein found in bacteria, called LH2. 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.

They used the Astra laser at the Science and Technology Facilities Council’s Rutherford Appleton Laboratory (RAL). It incorporates state-of-the-art technology developed in the Physics Department at Imperial College London to produce pulses of light with the right properties for this experiment, according to a University College release.

“Hopefully one day we will be able to harness the exquisite mechanisms that we learn about from molecules, whose function has been honed by evolution over hundreds of millions of years,” said Mercer. The researchers are currently applying this approach across the molecular biosciences and with electronic devices.

These findings were published in the Friday edition of Physical Review Letters.

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