How does femtochemistry work?
Femtochemistry works by using two precisely timed laser pulses: a 'pump' pulse to initiate a reaction and a 'probe' pulse to interrogate the system at a later time. By varying the delay between these pulses—down to a few femtoseconds—we can reconstruct the entire trajectory of atoms as they move. Think of it as a strobe light capturing a dancer's motion: each pulse freezes a moment, and together they form a movie. In my lab at Caltech, we applied this to simple molecules like iodine cyanide, watching the bond stretch and break. The key is the femtosecond timescale, which matches the vibrational period of chemical bonds—about 10 to 100 femtoseconds. This allows us to observe transition states directly, something previously impossible. My Nobel lecture, 'The Birth of Femtochemistry,' describes how we turned chemistry from a static science into a dynamic one, revealing the invisible choreography of atoms.
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