Scientists Capture Live Bacteria Portraits for the First Time
For the first time in history, researchers were able to observe a chemical bond being born.
Using an X-ray laser at the Department of Energy's SLAC National Accelerator Laboratory, scientists caught their first glimpse of the transition state in which two atoms begin to form a weak bond in the first steps of transforming into a molecule.
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The findings could lead to X-ray exploration of the molecular machinery at work in viral infections, cell division, photosynthesis and other processes.
"This is the very core of all chemistry. It's what we consider a Holy Grail, because it controls chemical reactivity. But because so few molecules inhabit this transition state at any given moment, no one thought we'd ever be able to see it," said Professor Anders Nilsson at the SLAC/Stanford SUNCAT Center for Interface Science and Catalysis and study lead author.
The experiment focused on cyanobacteria, or blue-green algae, an abundant form of bacteria that transformed the Earth's atmosphere 2.5 billion years ago by releasing breathable oxygen, making possible new forms of life that are dominant today.
Cyanobacteria play a key role in the planet's oxygen, carbon and nitrogen cycles.
Researchers sprayed living cyanobacteria in a thin stream of humid gas through a gun-like device. The cyanobacteria were alive and intact when they flew into the ultrabright, rapid-fire LCLS X-ray pulses, producing diffraction patterns recorded by detectors.
The X-ray laser pulses from SLAC's Linac Coherent Light Source (LCLS) allowed the team to observe this process by detecting changes in the arrangement of the atoms' electrons that occurred in quadrillionths of a second.
They were surprised to observe many of the reactants entered a transition state, but only a small number formed stable carbon dioxide without breaking apart.
The team is now working to measure the transition state in other catalytic reactions that can generate commercially-valuable chemicals.
The technique can capture about 100 images per second, amassing many millions of high-resolution X-ray images in a single day, researchers noted.
Details of the study were published in the journal, Nature Communications.