Animal and human life depends, either directly or indirectly, on plant life. And all plant life depends on extraordinarily precise biochemical machines that capture and convert light energy into energy that living cells can use. Researchers at the Argonne National Laboratory in Illinois have been using ultrafast spectroscopy to discover just how these systems work. Their most recent discovery has them baffled over the newfound complexity of photosynthesis in purple bacteria. It turns out that photosynthetic machinery is such advanced technology that it takes advantage of the quantum nature of light.

Researchers first cooled the photosynthetic bacteria to less than 150 degrees below freezing so that the superfast photon and electron interactions within bacteria’s light-harvesting protein complex would occur slow enough to investigate in more detail.

They shined one wavelength of light onto specific pigment molecules inside the biochemical light harvesting protein complexes. Each complex contains multiple pigments in precise arrangements. “Argonne scientists saw something no one had observed before: a single photon appeared to excite different chromophores [pigments] simultaneously,” according to an Argonne Labs feature story.1….

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