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Attosecond measurement of electrons in water

pte20220719015 Technology / Digitization, Research / Development

New ETHZ method used for more accurate research on water and faster electronics

Experimental drawing: an attosecond measurement of electrons in water clusters (Photo:

Experimental drawing: an attosecond measurement of electrons in water clusters (Photo:

Zurich (pte015 / 19.07.2022 / 13:55) –

Researchers at ETH Zurich They have developed a method by which electron motions in groups of water lasting only a few attoseconds can be temporarily resolved. The technology is said to be used to explore water more precisely and for faster electronics. Details were published in the journal Nature.

Use of intense ultraviolet laser

Experts investigated how water clusters are ionized with a short laser pulse in the extreme ultraviolet range. To do this, blocks are first created by forcing water vapor through a small nozzle under high pressure. Then the energy of the ultraviolet photons of the laser pulse ensures that one of the electrons is released into the cluster. There is a gap, a “hole”.

However, the electron is not released immediately after the pulse strikes, but with a small time delay. The magnitude of the delay depends on how the electron hole is distributed over the mass particles. Concretely, the delay lasts only a few attoseconds, a few billionths of a billionth of a second.

It is divided into two parts

In order to be able to measure the very short time intervals of a few attoseconds, the experts split a very intense infrared laser pulse into two parts, part of which was converted to intense ultraviolet by frequency doubling in an inert gas. They installed the two pulses and directed them to the water pools.

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The infrared laser pulse changes the energy of the electrons emitted by the UV laser pulse. The oscillation phase of an infrared laser pulse can be very precisely tuned using an interferometer. The number of ionization processes measured by the detectors varies depending on the phase of the oscillation. With these measurements, the researchers were finally able to directly read the time delay in ionization.