A methodology with a resolution of a quadrillionth of a second in slow motion

Observing and controlling ultrafast processes with attosecond resolution.

Measuring chamber at TUM’s Department of Physics
Measuring chamber at TUM’s Department of Physics. (Photo: Michael Mittermair / TUM)

Chemical processes are fast enough that they can’t be understood properly. This leads scientists at the Technical University of Munich to develop a technique with a resolution of a quadrillionth of a second. Scientists believe that the technique will help them better understand processes like photosynthesis and develop faster computer chips.

Ionization is an important step in various chemical processes. The reactions take place for just a couple of femtoseconds or even only a couple of hundred attoseconds. Since they run so quick, just the underlying and last items are known, yet not the response ways or the moderate items.

To watch such ultrafast forms, science needs an estimation innovation that is quicker than the watched procedure itself. Alleged “pump-probe spectroscopy” makes this conceivable. Usually, the laser pulse is used to set the reaction in motion.

Prof. Dr. Birgitta Bernhardt measuring at the Department of Physics at the Technical University of Munich
Prof. Dr. Birgitta Bernhardt measuring at the Department of Physics at the Technical University of Munich. (Photo: Michael Mittermair / TUM)

A moment, time-deferred beat questions the passing condition of the procedure. Various redundancies of the response with various time defer result in singular stop-movement pictures, which would then be able to be gathered into a “film cut”.

Scientists have now succeeded for the first time in combining two pump-probe spectroscopy techniques using the inert gas krypton. Doing this allowed them to enlight extremely fast ionization process with accuracy.

A study led Birgitta Bernhardt said, “Prior to our experiment, one could observe either which part of the exciting light was absorbed by the sample over time or measure what kind of and how many ions were created in the process. We have now combined the two techniques, which allows us to observe the precise steps by which the ionization takes place, how long these intermediate products exist and what precisely the exciting laser pulse causes in the sample.”

With this technique, scientists can even control the dynamics of ionization process.

Bernhardt said, “This kind of control is a very powerful instrument. If we can precisely understand and even influence fast ionization processes, we are able to learn a lot about light-driven processes like photosynthesis – especially about the initial moments in which this complex machinery is set into motion and which is hardly understood to date.”

“The technique could also develop faster computer chips in which the ionization of silicon plays a significant role. If the ionization states of silicon can not only be sampled on such a short time scale but can also be set – as the first experiments with krypton suggest – scientists might one day be able to use this to develop novel and even faster computer technologies.”

The study ‘Ultrafast quantum control of ionization dynamics in krypton’ is published online in Nature Communications.