Watching the quantum race of electrons


For the first time ever, a German team of physicists has observed the race of two electrons that are liberated from atoms in the course of photoionization, i.e. under the influence of laser radiation. In order to resolve the electron’s movement during only 50 femtoseconds, scientists from Hamburg and Kiel Universities and DESY (Deutsches Elektronen-Synchrotron – one of the world's leading accelerator centres) used an ultra fast terahertz streak camera in combination with a free-electron-laser. The experimental findings will improve the rapidly evolving free-electron-laser technology used in many fields of science – from physics to biology.

The interaction of electrons is crucial for the properties of atoms and molecules which are the building blocks of living organisms and all man-made systems. Understanding the electronic processes in atoms is therefore essential for numerous future applications – from medicine to engineering.
When a photon of sufficiently high energy hits an atom it may kick out an electron. Albert Einstein termed this process “photo ionization” (photo effect) back in 1905 and thus confirmed a theory of the Kiel scientist Max Planck that would soon revolutionize physics: quantum mechanics. Quantum mechanics predicts that the liberated electron runs away from the atom, behaving like a wave. In the 1920s, Lise Meitner and Pierre Auger independently discovered another effect: When applying specific photon energy during photo ionization, a second electron, termed Auger electron, may be liberated from the atom. In cases when the Auger electron runs in the same direction as the first electron a quantum race of electron waves starts.

This race of the two electrons is extremely fast, taking between 1 and 100 femtoseconds (1fs=0.000 000 000 000 001s). “Until now, no experiment has resolved this race in time”, says Professor Markus Drescher of the Institute for Experimental Physics at Hamburg University, leader of the experimental part of the project. The key to observing the electron race in the current study was to combine the free-electron laser FLASH at DESY in Hamburg with an ultrafast streak camera. By accurately controlling the timing of the two electromagnetic fields generated by the laser and the camera, the scientists were able to reconstruct the electrons’ movement and energy exchange. In this manner, the physicists detected how the Auger electron passes the first one.

At the Institute of Theoretical Physics and Astrophysics of Kiel University, the research group of Professor Michael Bonitz tried to reproduce the experimental results with computer simulations. “After testing several possible explanations for the measured results, our PhD student Sebastian Bauch verified that the experiment indeed observed the quantum race of two electrons”, adds Bonitz. The Kiel physicists collaborate with the experimentalists from Hamburg within the project “FLASH” funded by the German Federal Ministry of Education and Research.

The results give valuable information on key properties of the involved laser pulse. The free electron laser technology has been rapidly evolving in recent years. In this context the present results will be important for improving the quality and precision of future free electron laser experiments.

Christian-Albrechts-Universität zu Kiel (CAU)

Request information now

Recommend news PDF version / Print

Share on

More about Christian-Albrechts-Universität zu Kiel
  • News

    The hidden Nano Power Switch

    The increasing miniaturisation in electronics will result in components which consist of only a few molecules, or even just one molecule. Tiny wires are required to connect these to an electrical circuit at the nano level. An international research team from Kiel University (CAU) and the Do ... more

    Tugging at cells with molecules and light

    Everyone is made up of approximately 100 trillion cells – if they were laid end to end, they would circle the globe 60 times. Most of these cells arise from mitosis and differentiation of a single egg cell. To orientate themselves, they constantly explore their environment and communicate w ... more

    UV-sensors from the oven

    Placed in fire detectors and water treatment units UV-sensors can save lives; also in many areas of industry and environment the demand for these devices is rising steadily. Scientists of Kiel University have been able to ”bake” nanostructures within seconds, in order to fabricate very fast ... more

More about Uni Hamburg
  • News

    X-ray laser reveals chemical reaction

    What happens when a chemical bond is broken? That question was recently answered with the help of a so-called free electron x-ray laser, which makes it possible to follow in real time how bindings in a molecule are changed and broken. The study, published in Science, found, among other thin ... more

    Scientists measure soot particles in flight

    For the first time, air-polluting soot particles have been imaged in flight down to nanometre resolution. Pioneering a new technique, the international team, including researchers from DESY, snapped the most detailed images yet of airborne aerosols. “For the first time we can actually see t ... more

    Lattice of magnetic vortices

    Physicists at Hamburg and Kiel University and the Forschungszentrum Jülich have found for the first time a regular lattice of magnetic skyrmions – cycloidal vortex spin structures of exceptional stability – on a surface. This fascinating magnetic structure was discovered experimentally at t ... more

More about Deutsches Elektronen-Synchroton DESY
  • News

    Scientists observe nanowires as they grow

    At DESY's X-ray source PETRA III, scientists have followed the growth of tiny wires of gallium arsenide live. Their observations reveal exact details of the growth process responsible for the evolving shape and crystal structure of the crystalline nanowires. The findings also provide new ap ... more

    Grazing light for rapid events

    An international team of scientists has developed a new experimental method at the FLASH X-ray laser which allows the sequence of events involved in a process to be observed using a single, ultrashort pulse of light from FLASH. Their method is called “X-ray streaking” and enables researcher ... more

    Groundbreaking experimental method will speed up protein analysis substantially

    An international team of scientists has for the first time used an X-ray free-electron laser to unravel the structure of an intact virus particle on the atomic level. The method used dramatically reduces the amount of virus material required, while also allowing the investigations to be car ... more

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE