The shortest amount of time ever measured
A light particle needs just 247 zeptoseconds to cross a molecule made up of two hydrogen atoms. Scientists working with Reinhard Dörner from the University of Frankfurt have now determined – and, according to their own statements, achieved a record: never before has a shorter period of time been measured. A zeptosecond is a trillionth of a billionth of a second. In other words, it is 10-21 seconds.
They describe their experimental setup in the specialist magazine “Science”. They bombarded the hydrogen molecule (H2) with a high-energy light particle, an X-ray photon. On its way it first shot one electron of the hydrogen molecule out of the compound, then the other. Because the electrons behave both like a particle and like a wave, each of the two “hits” generated its own electron wave. Both waves overlap and generate an interference pattern that Dörner’s team mapped using a sensitive and ultra-fast measuring device. This so-called COLTRIMS reaction microscope was co-developed by Dörner’s working group and, like the source of its X-ray photons, is located at the DESY accelerator center in Hamburg.
The time that elapses between the generation of the two electron waves is reflected in a distortion of the interference pattern. And this in turn allowed the experts to infer the exact timing of the events: a maximum of 247 zeptoseconds passed between the two “hits”, “depending on how far the two atoms in the molecule were from each other from the point of view of light,” explains the Frankfurt researcher Sven Grundmann, first author of the study, in a press release.
This shows that even in such a tiny molecule like this, the electron shell cannot react to the incoming light everywhere at the same time, explains Dörner. Instead, the information only propagates at the speed of light, which then causes the characteristic distortion in the interference pattern.
Researchers made their first breakthrough in zeptosecond physics in 2016. The time they determined, which they determined with the help of lasers, was 850 zeptoseconds.
This article was published originally by spektrum.de
Article source: spektrum.de
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