First movie of energy transfer in photosynthesis solves decades-old debate

[OKIsItJustMe]

http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_1-12-2016-16-46-44

[font face=Serif][font size=5]First movie of energy transfer in photosynthesis solves decades-old debate[/font]

by Hayley Dunning, Thomas Angus [Photographer]
23 December 2016

[font size=4]Using ultrafast imaging of moving energy in photosynthesis, scientists have determined the speed of crucial processes for the first time.[/font]

[font size=3]This should help scientists understand how nature has perfected the process of photosynthesis, and how this might be copied to produce fuels by artificial photosynthesis.

During photosynthesis, plants harvest light and, though a chemical process involving water and carbon dioxide, convert this into fuel for life. A vital part of this process is using the light energy to split water into oxygen and hydrogen.

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Now, using ultrafast imaging of electronic excitations that uses small crystals of Photosystem II, scientists from Imperial College London and Johannes Kepler University (JKU) in Austria have shown that the slowest step is in fact the process through which the plants harvest light and transfer its energy through the antennae to the reaction centre.

The new insights into the precise mechanics of photosynthesis should help researchers hoping to copy the efficiency of natural photosynthesis to produce green fuels. Study author Dr Jasper van Thor, from the Department of Life Sciences at Imperial, said: "We can now see how nature has optimised the physics of converting light energy to fuel, and can probe this process using our new technique of ultrafast crystal measurements.

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http://dx.doi.org/10.1038/NCOMMS13977

[eppur_se_muova]

1. Ummm ... "hoping to copy the efficiency of natural photosynthesis ..."

For actual sunlight, where only 45% of the light is in the photosynthetically active wavelength range, the theoretical maximum efficiency of solar energy conversion is approximately 11%. In actuality, however, plants do not absorb all incoming sunlight (due to reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels) and do not convert all harvested energy into biomass, which results in an overall photosynthetic efficiency of 3 to 6% of total solar radiation.[1]

https://en.wikipedia.org/wiki/Photosynthetic_efficiency

[OKIsItJustMe]

2. Note that the OP refers to "energy transfer"

http://www.plantcell.org/content/early/2012/05/21/tpc.112.097972.full.pdf

[font face=Serif][font size=5]Photosynthetic Quantum Yield Dynamics: From Photosystems to Leaves[/font]

[font size=3]…

Three major causes for the wavelength dependence of the quantum yield for absorbed photons have been identified (i.e., absorption by photosynthetic carotenoids, absorption by nonphotosynthetic pigments, and an imbalanced excitation of the two photosystems) (Terashima et al., 2009). Photosynthetic carotenoids have absorption maxima for blue wavelengths and differ in their efficiency (35 to 90%) for excitation energy transfer to chlorophylls, depending on the type of carotenoid and its position within the photosynthetic apparatus, whereas the energy transfer efficiency in the antenna complexes from chlorophyll to chlorophyll is 100% (Croce et al., 2001; de Weerd et al., 2003a, 2003b; Caffarri et al., 2007). …[/font][/font]