Scientists have tracked ultra-fast structural changes that occur when ring-shaped gas molecules burs open for the first time.
The molecules are commonly seen in biochemistry, and for the basis of a variety of drug compounds, SLAC National Accelerator Laboratory reported. The study could lead to the realization of a range of X-ray studies of gas-based chemical reactions that would provide insight into key biological processes.
To make their findings, the researchers turned the full sequence of steps in this basic ring-opening reaction into digital animations, creating a "molecular movie" that demonsted the structural changes. The method reveals how gas-phase molecules transform during chemical reactions in only a matter of femtoseconds (a millionth of a billionth of a second.)
"This fulfills a promise of LCLS: Before your eyes, a chemical reaction is occurring that has never been seen before in this way," said Mike Minitti, a SLAC scientist who led the experiment in collaboration with Peter Weber at Brown University. The results are featured in the June 22 edition of Physical Review Letters. "LCLS is a game-changer in giving us the ability to probe this and other reactions in record-fast timescales, down to the motion of individual atoms."
The study focused on the gas form of 1,3-cyclohexadiene (CHD), which is a rin-shaped organic molecule found in pine oil. The team tracked how the ring unfurled after a bond between two of its atoms was broken, causing it to morph into an almost linear molecule called a hexatriene.
"There had been a long-standing question of how this molecule actually opens up," Minitti said. "The atoms can take different paths and directions. Tracking this ultimately shows how chemical reactions are truly progressing, and will likely lead to improvements in theories and models."
The research allowed the team to show the changing motion and position of atoms in a comprehensive movie consisting of intervals representing 25 quadrillionths of a second each.
"This study can serve as a benchmark and springboard for larger molecules that can help us explore and understand even more complex and important chemistry," Minitti said.
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