Femtosecond Week

Five days—that's 432,000,000,000,000,000,000 femtoseconds—of ultrafast science at SLAC

April 17 – 21, 2017


noun | fem·to·sec·ond | \ˈfem(p)-tə-ˌse-kənd \

10−15 or one quadrillionth of a second

What is a Femtosecond?

~ An interview with SLAC scientist Ryan Coffee ~

Why Study in Femtoseconds?

~ An introduction by physicist Phil Bucksbaum ~

Director of the PULSE Institute at SLAC and Stanford University

SLAC physicist Phil Bucksbaum

The text on this screen may appear stable enough, but every molecule, atom, and electron in it is in constant motion. The laws of quantum physics require that on the atomic scale nothing is ever truly at rest. Nano-sized motion also keeps us warm, cooks our food, lights our smartphones, and enables all of our senses of hearing, sight, smell, taste, and touch.

Until recently this tiny, rapid motion was always hidden from view because it is just too small and too fast to record in real time. But now new tools like the bright X-ray pulses at the Linac Coherent Light Source (LCLS) and the advanced ultrashort pulse lasers and electron beams at SLAC can capture snapshot images that last only femtoseconds—quadrillionths of a second. This is a flash of light short enough to freeze the motion of atoms in molecules. Still faster probes, under development now by scientists at SLAC, will soon be able to track the motion of electrons as they cross single chemical bonds in less than a single femtosecond.

Scientists piece these snapshots together to make slow-motion molecular movies that show how nature works. These femtosecond movies can help scientists develop novel materials and new chemicals, and help us to understand how all processes in nature depend on femtosecond motion on the atomic scale.

During Femtosecond Week, learn more about these experiments and the researchers who are making discoveries at this frontier of science.

Scales of Time

~ From the universe to the atom ~

Take a journey through the universe, from processes that take billions of years to chemical reactions that occur in a millionth of a billionth of a second—and faster! Our preferred browser is Google Chrome.

Follow SLAC on Social Media

~ Stay tuned for #femtoweek ~

Director of LCLS Mike Dunne

~ Twitter chat with LCLS Director Mike Dunne ~

Mike Dunne (@MikeDunne9), director of the Linac Coherent Light Source (LCLS), joined us on April 18 for a Twitter chat to answer questions about X-ray lasers and ultrafast science. See the Twitter chat here.

Virtual Tours

The Linac Coherent Light Source (LCLS) at SLAC allows scientists to see the world in femtosecond resolution. Click on the images below to take virtual tours of the undulator hall and the Near Experimental Hall (NEH) at LCLS. Also check out our LCLS album on Flickr for photos of the facility.


Undulator Hall

Inside the 170-meter-long undulator hall, 33 precisely aligned magnets wiggle accelerated electrons to generate X-ray laser pulses.


Near Experimental Hall

The Near Experimental Hall houses three of the seven LCLS experimental hutches—AMO (Atomic, Molecular & Optical Science), SXR (Soft X-ray Materials Science) and XPP (X-ray Pump Probe).


~ Follow us: #femtoweek @SLAClab and come back for more ~

  • There are 605 quintillion—605,000,000,000,000,000,000—femtoseconds in a week. Thanks for joining us for Femtosecond Week!

  • One attosecond is time it takes for light to travel the length of two hydrogen atoms.

  • Vibrations of atoms in iodine molecules occur in 300 femtoseconds. Learn more ultrafast materials science tomorrow during Femtosecond Week.

  • We can watch certain chemical reactions occur in femtosecond frames:

  • A femtosecond is to 1 second as 1 second is to 31.7 million years.

  • To date, the shortest X-ray laser pulses delivered by LCLS last 5 femtoseconds, about the same time a molecule takes to lose an electron.

  • As fast as the blink of an eye? That’s still about 350,000,000,000,000 femtoseconds.

  • “Femto” means a factor of 10-15. It comes from the Danish word for fifteen, “femten”.

  • A femtosecond is 1 quadrillionth of a second.

Beyond Femtoseconds

Hopefully you've discovered this week how femtosecond science provides revolutionary views of some of nature’s fastest phenomena. You now know how mind-bogglingly fast a femtosecond passes, and you might be thinking things couldn't get much faster. Well, let’s talk about the attosecond.

One attosecond—a billionth of a billionth of a second, or a thousandth of a femtosecond—is just long enough for light to travel the width of a few hydrogen atoms, and scientists are only beginning to understand this largely unexplored time domain.

Some researchers believe that a few hundred attoseconds is the sweet spot for exploring the very heart of chemistry. Attosecond motions of electrons in atoms and molecules set the stage for what happens on slower timescales. While femtosecond snapshots reveal how individual atoms rapidly move around during chemical reactions, attoseconds would unearth what’s going on behind the scenes.

Building on the groundbreaking work used for femtosecond science, SLAC researchers and engineers are at the forefront of developing the tools to study these fundamental aspects of chemistry and develop the theoretical framework for attosecond science. They use high-power lasers to extract attosecond light pulses from atoms and work on techniques to turn femtosecond pulses from the Linac Coherent Light Source (LCLS) X-ray laser into much shorter light flashes.

What will scientists uncover in the attosecond realm, and what will these ultrafast discoveries make possible in the fields of chemistry, materials science, biology and energy research? Stay tuned. In the field of ultrafast science, time flies.

Before You Go…

~ Download the SLAC ultrafast science factsheet (PDF) ~

Ultrafast Science Factsheet (PDF)


~ Femtosecond Week is a SLAC Communications production ~

  Project led by Amanda Solliday

  Web design by Yvonne Tang

  Written and edited by Glennda Chui, Manuel Gnida, Kathryn Jepsen, Amanda Solliday and Angela Anderson

  Scales of Time interactive by Chris Smith and Andy Freeberg

  Virtual tours created by Laura Boon at Matterport with assistance from Hila Shilon

  Graphic design by Greg Stewart and Terry Anderson

  Photography by Chris Smith, Andy Freeberg and Dawn Harmer

  Video by Matt Beardsley, Greg Stewart and Andy Freeberg

  Promotion by Andrew Gordon, Tracy Chalmers, Katie Puglisi-Chan, Melinda Lee and Amanda Solliday

  Additional scientific input provided by Mike Dunne, Bill White, Phil Bucksbaum, Tom Abel, Sebastien Boutet, Alan Fry, Tony Heinz, JoAnne Hewett, Andy MacKinnon, Lia Merminga, Mike Minitti, Joseph Robinson and Xijie Wang

  Guidance provided by SLAC Director of Communications Melinda Baker

  For questions or comments, contact the SLAC Office of Communications at communications@slac.stanford.edu.

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, Calif., SLAC is operated by Stanford University for the U.S. Department of Energy's Office of Science.

LCLS is a DOE Office of Science User Facility. Ultrafast science at SLAC is supported by the DOE Office of Science.

SLAC National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.