Ul­tra-High-Speed ‘Elec­tron Cam­era’ can open up deeper molec­u­lar stud­ies

Chemical Industry Digest - - Science Pages -

An ex­tremely fast “elec­tron cam­era” at the Depart­ment of En­ergy’s SLAC Na­tional Ac­cel­er­a­tor Lab­o­ra­tory has pro­duced the most de­tailed atomic movie of the de­ci­sive point where mol­e­cules hit by light can ei­ther stay in­tact or break apart. The re­sults could give a bet­ter idea of how mol­e­cules re­spond to light in pro­cesses that are cru­cial for life, like pho­to­syn­the­sis and vi­sion, or that are po­ten­tially harm­ful, such as DNA dam­age from ul­tra­vi­o­let light.

Re­searchers looked at a gas whose mol­e­cules have five atoms each. They watched in real time how light stretched the bond be­tween two atoms in the mol­e­cules to a “point of no re­turn,” send­ing the mol­e­cules on a path that ei­ther fur­ther sep­a­rated the atoms and cleaved the bond or caused the atoms to vi­brate while pre­serv­ing the bond.

“The start­ing and end points of a chem­i­cal re­ac­tion are of­ten ob­vi­ous, but it’s much more chal­leng­ing to take snap­shots of the rapid re­ac­tion steps in be­tween,” said post­doc­toral re­searcher Jie Yang, the study’s lead au­thor from SLAC’s Ac­cel­er­a­tor Direc­torate and the Stan­ford PULSE In­sti­tute. “The cross­roads where a mol­e­cule can do one thing or another are an im­por­tant fac­tor in de­ter­min­ing the out­come of a re­ac­tion. Now we’ve been able to ob­serve di­rectly for the first time how the atomic nu­clei of a mol­e­cule re­ar­range at such an in­ter­sec­tion.”

The com­plete re­port on the study is avail­able on SLAC’s web­site.

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