Florida man is world's fastest flasher: Just 53 quintillionths of a sec


Beam of light

Physicists at the University of Central Florida have developed the world's fastest X‑ray pulse, at 53 attoseconds.

Blink and you'll really, really miss it. At 53 quintillionths (53 x 10‑18) of a second, the flash is 15 orders of magnitude faster than the blink of an eye. The beam travels less than one-thousandth of the diameter of a human hair in that time.

The group led by Zenghu Chang, a professor of physics, optics and photonics, also held the previous record in 2012 for the fastest light pulse at 67 attoseconds. The new record is not only faster, but the light is at a shorter wavelength too, allowing scientists to penetrate the "water window" – a region where carbon atoms absorb the light more strongly than water molecules.

The results were published in Nature Communications last week. Just like a camera flash captures an image, the X‑ray pulse will allow researchers to take a snapshot of electrons and atoms in cells. Over time, the pictures will give researchers a chance to track biological processes like photosynthesis unfolding at the atomic scale.

Prof Chang said on Monday:

Such attosecond soft X‑rays could be used to shoot slow-motion video of electrons and atoms of biological molecules in living cells to, for instance, improve the efficiency of solar panels by better understanding how photosynthesis works.

It may also benefit technology. The energetic X‑ray pulses can interact with bound electrons in matter, and can track how, say, the particles move in RAM and flash memory chips in mobile phones and computers.

Attosecond pulses require using ultra-fast femtosecond (10‑15) lasers with a long wavelength.

"An X‑ray burst is produced by colliding a high energy electron with the nucleus of an atom. The electron is first released from an atom by a strong laser field, then is accelerated by the same laser field to reach high energy (300 eV in this case). All this happened within half a laser cycle and this process repeats every half cycle. One cycle is 5.6 femtoseconds for our laser.

"To generate a single isolated attosecond burst, the driving laser pulse was manipulated in a special way by a scheme named 'polarization gating' so that only one collision occurs per laser shot," Chang explained to The Register.

The research was partly funded by the US defense research arm, DARPA, and the US Air Force Office of Scientific Research. ®

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