Ultrafast
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In physics, the adjective ultrafast describes events that occur on femtosecond (10−15 s) to picosecond (10−12 s) timescales. Once impossible to observe, ultrafast phenomena are now extensively studied thanks to advances in the design of pulsed dye lasers and more recently with the invention of the pulsed Ti:sapphire laser, which can create pulses as short as 5 femtoseconds (roughly two optical cycles) when mode-locked.
[edit] Applications
The ability to study phenomena that happen on very short timescales is useful in many fields of science. Ultrafast lasers are currently being used in many applications including the study of femtosecond dynamics of electrons in solids, the creation of small, tabletop-sized fusion experiments, the manipulation and monitoring of chemical reactions, the modification and imaging of magnetic surfaces, and the creation and study of plasmas. They have also been used extensively in microscopy.
The 1999 Nobel Prize in Chemistry was awarded to Ahmed H. Zewail for using ultrashort pulses to observe chemical reactions on the timescales they occur on, opening up the field of femtochemistry.
