Femtosecond stimulated Raman spectroscopy on GFP involves hitting the protein molecule with an approximately 80 femtosecond pulse of ultraviolet light, which excites many vibrational modes in the molecule, and then a one-two punch of picosecond red and femtosecond white light to stimulate Raman emission. The spectrum of emitted signals tells researchers the vibrational modes of various parts of the molecule. If the molecule is in the middle of a reaction, the emitted light at different time delays tells the researcher the various steps the molecule goes through during the reaction. “Now, we can get very, very high resolution structure down to 10-25 femtoseconds,” Mathies said.

That’s femtoseconds, with an ‘f’. Wild!

Image credit: Renee Frontiera & Chong Fang/UC Berkeley