Home ” Scientists have measured the smallest unit of time to date
The time it takes for a photon of light to pass through a molecule has been measured: 247 zeptoseconds or “trilliardths of a second. ”
0.00000000000000000000247 seconds. This is the time it takes for light to pass through a hydrogen atom, according to a new study published in Science. It is the smallest unit of time ever measured and described. It is of the order of zeptosecond (247 zeptoseconds, in this case), also translated as 10-21 seconds or a “trillionth” of a second. Until then, the shortest time span measured in a physico-chemical process was 850 zeptoseconds or 0.85 attoseconds (10-18), in 2016, according to LiveScience. And there are still a few years, the time of association or dissociation of atoms into molecules, of the order of the femtosecond (10-15), was still considered the short. It even earned the Egyptian researcher who had described it, Ahmed Zewail, a Nobel Prize in chemistry in 1999.
How to measure such a short time?
To arrive at this truly infinitesimal measurement, the German physicist Reinhard Dörner and his colleagues at Goethe University in Frankfurt called upon a particle accelerator located in Hamburg. They inserted a hydrogen atom into it in a so-called desired orbital position. They then targeted it with an X-ray, a source of light and therefore a photon. The researchers were thus able to cause a photoionization reaction – when a photon passes through a chemical element and the latter loses one or more electrons. This reaction leads to the confrontation of tiny electromagnetic waves. The researchers nevertheless managed to observe it using an interferometric microscope (the instrument necessary to observe such a phenomenon) called COLTRIMS (for “Cold Target Recoil Ion Momentum Spectroscopy”). “We have managed to observe, for the first time, that the electronic shell of a molecule does not react everywhere at the same time to a photon of light, underlines Reinhard Dörner in a press release relayed by LiveScience. In reality, there is a very slight time lag, corresponding to the time that information passes through the molecule itself – namely, the speed of light. “
