Scientists See Photosynthesis Happening in Detail, Thanks to New Laser Technique

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What if we could mimic how plants, algae, and bacteria harvest sunlight to create better solar panels? New research published Wednesday in Nature explores the molecular nitty-gritty of photosynthesis, and it may help us get closer to making this a reality.

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Young students learn about photosynthesis, the process by which plants convert sunlight and water into energy. But despite how seemingly basic the concept is, there are actually lots of mysteries remaining about how it works: namely, the photophysics of the process, the atomic and molecular changes that occur when a plant absorbs sunlight.

"The (quantum) electronics of the plant world is pretty spectacular," study author Tomi Baikie, a fellow at the Cavendish Laboratory at Cambridge University, said in an email to Earther.

Part of the problem with fully understanding photosynthesis is that much this process moves far too quickly for many traditional monitoring systems; we're talking about speeds on the scale of a millionth of a millionth of a second. To try to watch these swift cellular changes, the team developed a technique using super-fast spectroscopic techniques—laser pulses aimed at live cell samples.

These lasers, Baikie explained, take "photos" of the cells at a rate "a million billion times faster than your iPhone"; the technique was dreamed up in a conversation with another of the study's coauthors at a college pub. "We didn't quite expect it to work—but it worked really, really well," Baikie said. "This meant we have a new tool to understand cells."

The results of these laser observations were surprising. The researchers found that electrons crucial to photosynthesis are actually extracted from cells much earlier in the process than previously thought.

"Many attempts have been made to try to 'steal' electrons from photosynthesis as early as possible after the first light absorption step," study author Jenny Zhang, a fellow at Cambridge's Yusuf Hamied Department of Chemistry, told Earther in an email. "Achieving this would open up many exciting possibilities where photosynthetic cells and their components can serve as self-generating, self-repairing catalysts that cannot be replicated by artificial systems. My research has been trying to achieve this for the last decade, using many strategies to try to steal the electrons; however, we have never had the ability to 'see' where the electrons are being stolen from within the cells."

While this all may sound wonky, there is some potentially game-changing information here for a range of future applications, from biofuels to developing more efficient crops. And there are also exciting implications for renewable energy. Plants are very good at making light into energy, converting solar electrons with close to 100% efficiency. Understanding how exactly that process works could help us mimic it.

"All it takes is a few fundamental breakthroughs to completely change the field," Zhang said. "Such breakthroughs require time, but also investment in fundamental science and interdisciplinary research. This work is a beautiful demonstration of this, we have changed the goal posts of which this technology can be."