The ability to see molecular motions in real time offers insights into chemical dynamics processes that were unthinkable just a few decades ago, the researchers say, and may ultimately help in optimizing reactions and designing new types of chemistry.
"For many years, chemists have learned about chemical reactions by essentially studying the molecules present before and after a reaction has occurred," said Brian Stankus, a recent Ph.D. graduate from Brown University and co-lead author on the paper. "It was impossible to actually watch chemistry as it happens because most molecular transformations happen very quickly. But ultrafast light sources like the one we used in this experiment have enabled us to measure molecular motions in real time, and this is the first time these sorts of subtle effects have been seen with such clarity in an organic molecule of this size."
Work - Collaboration - Chemists - Brown - Scientists
The work is a collaboration between chemists from Brown, scientists at SLAC National Accelerator Laboratory and theoretical chemists from the University of Edinburgh in the U.K. The team was led by Peter Weber, professor of chemistry at Brown.
For the study, the researchers looked at the molecular motions that occur when the organic molecule N-methyl morpholine is excited by pulses of ultraviolet light. X-ray pulses from SLAC's Linac Coherent Light Source (LCLS) were used to take snapshots at different stages of the molecule's dynamic response.
Molecules - UV - Light - Response - Fractions
"We basically hit the molecules with UV light, which initiates the response, and then fractions of a second later we take a "picture" -- actually we capture a scattering pattern -- with an x-ray pulse," Stankus said. "We repeat this over and over, with different intervals between the UV pulse and x-ray pulse to create a time-series."
The x-rays scatter in particular patterns depending on the structure of molecules. Those patterns are analyzed and used...
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