shortest x-ray laser pulse
ETH researchers achieved in reducing the duration of an X‑ray laser pulse to only 43 attoseconds. It is the first time to observe the movement of electrons during chemical reactions in slow motion.
To understand the dynamics of chemical reaction, scientists studied the movements of atoms and molecules on their basic time scale. Molecules rotate in the range of picoseconds, their atoms vibrate in the range of femtoseconds, and the electrons move in the range of attoseconds.
Professor Hans Jakob Wörner and his team succeeded in generating the world’s shortest laser pulse with a duration of only 43 attoseconds. This laser pulse is the shortest controlled event that created by humans. Now, the researchers can observe how electrons move within a molecule or how chemical bonds formed.
inner-shell electrons
The researchers generate a soft X-ray laser pulse with a very large spectral bandwidth. As a result, various elements, including phosphorus and Sulphur directly observed by exciting their inner-shell electrons. Both elements present in bio-molecules, and it is possible to observe them with unprecedented time resolution.
But what is the advantage of being able to observe the reaction steps now with even higher resolution? “The faster a charge transfer can take place, the more efficiently a reaction can proceed” says Prof. Wörner.
For example, in rhodopsin, a visual pigment in the retina, the photosensitive molecule retinal pre-arranged in such a way that its structure can change extremely fast through the absorption of only a single photon. This enables the visual process even in twilight. A much slower reaction would provide vision impossible because the energy of the photon converts to heat in only a few picoseconds.
The Attosecond laser spectroscopy not only suitable for mere observation, also directly manipulated chemical reactions.
The researchers already working on the next generation of even shorter laser pulses. These will make it possible to record even more detailed images, and a wider X-ray spectrum even more elements can probe than before.
More information: [Optics express]
