What is a Femtosecond?

Ryan Coffee, scientist at SLAC’s Linac Coherent Light Source X-ray laser, explains, “What is a femtosecond?” 

so sound travels a foot in one

millisecond if I go another factor of a

thousand I'm at a microsecond another

factor of a thousand is at a nanosecond

that's how long it takes light to travel

a foot if I go note another factor of a

thousand I'm at a picosecond and another

factor of a thousand

is a femtosecond so the first steps in

the chemical reactions that happen in

your blood with the heme group moving

oxygen around or photo absorption in

light harvesting in the plants in your

garden or even the formation of plaques

in your blood that give you diabetes or

degenerative diseases the first steps in

all of these happen on the femtosecond

time scale

the field of ultra-fast science has been

used in chemistry for probably 10 20

years now and it's delivered much of the

fundamental understanding of how light

interacts with molecules and so the idea

is now we can make these molecular

movies because we have now x-rays that

can probe the molecules at exactly that

natural timeframe of the reaction now

that we have x-rays to see at the scale

of molecules and we have the time frame

with femtoseconds that are on the scale

of how fast these molecules move how

they change their shape we can start to

look at why nature made the molecules

the shapes that she did and so that's

where I think science has finally gotten

us to this level where we can look at

the time frame of the individual

molecules during the reaction


Matt Beardsley & Andy Freeberg/SLAC National Accelerator Laboratory

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