Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Distorted Atoms

06.11.2019

In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.

An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort extreme-ultraviolet (XUV) laser pulses [1]. Such doubly excited states are short-lived, decaying in just a few femtoseconds (10⁻¹⁵ seconds) via autoionization: one electron falls back into the ground state while the other one escapes from the atom.


Schematic illustration for the powerful excitation of an electron pair (blue) in the helium atom by an intense ultrashort XUV laser pulse (violet).

Graphics: MPIK

To achieve a significant population of this state, the rate of excitation has to be faster than the decay rate. It is like pumping water into a reservoir which has a significant leak.

This experiment has been performed at the Free-Electron Laser in Hamburg (FLASH), which delivers intense XUV laser pulses with a sufficiently short interaction time. Theoretical modelling predicts an efficient excitation of the electron pair by such pulses.

Temporarily, the excited-state population may even exceed that of the ground state, creating a population inversion. This laser-controlled quantum dynamics with two active electrons manifests itself in a significant modification of the XUV light absorption, which has been observed in the experiment (see lower part of Figure).

In a second experiment at FLASH, the team around the Heidelberg physicists carried out XUV-pump XUV-probe transient absorption spectroscopy of doubly charged neon ions [2]. Here, the free-electron laser is used both for the production of the ions as well as for the spectroscopy.

It reveals a nonlinear coherence spike on a few-femtosecond timescale which relates to the coherence time of a free-electron laser pulse. It thus represents a key step towards the implementation of two- and multidimensional spectroscopy approaches, even for statistically fluctuating free-electron lasers and gas-phase samples. The scientific key result of this experiment was the direct measurement of shifts of atomic energy levels induced by nonlinear interaction with the intense XUV laser.

Altogether, these results open up new routes to explore extreme light-matter interaction and for element-specific quantum control with resonant nonlinear optics at short wavelengths.

Tuning the distortion of specific chemical elements within molecules could, in the future, revolutionize our way of thinking about chemistry.

Wissenschaftliche Ansprechpartner:

Dr. Christian Ott
Tel: (+49)6221-516-577
E-Mail: christian.ott@mpi-hd.mpg.de

Dr. Thomas Ding
Tel: (+49)6221-516-332
E-Mail: thomas.ding@mpi-hd.mpg.de

Prof. Dr. Thomas Pfeifer
Tel: (+49)6221-516-380
E-Mail: thomas.pfeifer@mpi-hd.mpg.de

Originalpublikation:

[1] Strong-Field Extreme-Ultraviolet Dressing of Atomic Double Excitation
Christian Ott et al.
Physical Review Letters 123,163201 (2019), DOI: https://doi.org/10.1103/PhysRevLett.123.163201

[2] Nonlinear Coherence Effects in Transient-Absorption Ion Spectroscopy with Stochastic Extreme-Ultraviolet Free-Electron Laser Pulses
Thomas Ding et al.
Physical Review Letters 123, 103001 (2019), DOI: https://doi.org/10.1103/PhysRevLett.123.103001

Weitere Informationen:

https://www.mpi-hd.mpg.de/mpi/en/research/scientific-divisions-and-groups/quantu... Division Pfeifer at MPIK - Excited Atoms and Molecules in Strong Fields
https://flash.desy.de/ Free-Electron Laser FLASH
https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.123.163201 Distorting Helium Atoms with XUV Light - Physics Synopsis

Dr. Bernold Feuerstein | Max-Planck-Institut für Kernphysik
Further information:
http://www.mpi-hd.mpg.de

More articles from Physics and Astronomy:

nachricht Molecules move faster on a rough terrain
20.01.2020 | Université libre de Bruxelles

nachricht Spider-Man-style robotic graspers defy gravity
20.01.2020 | American Institute of Physics

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Programmable nests for cells

KIT researchers develop novel composites of DNA, silica particles, and carbon nanotubes -- Properties can be tailored to various applications

Using DNA, smallest silica particles, and carbon nanotubes, researchers of Karlsruhe Institute of Technology (KIT) developed novel programmable materials....

Im Focus: Miniature double glazing: Material developed which is heat-insulating and heat-conducting at the same time

Styrofoam or copper - both materials have very different properties with regard to their ability to conduct heat. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the University of Bayreuth have now jointly developed and characterized a novel, extremely thin and transparent material that has different thermal conduction properties depending on the direction. While it can conduct heat extremely well in one direction, it shows good thermal insulation in the other direction.

Thermal insulation and thermal conduction play a crucial role in our everyday lives - from computer processors, where it is important to dissipate heat as...

Im Focus: Fraunhofer IAF establishes an application laboratory for quantum sensors

In order to advance the transfer of research developments from the field of quantum sensor technology into industrial applications, an application laboratory is being established at Fraunhofer IAF. This will enable interested companies and especially regional SMEs and start-ups to evaluate the innovation potential of quantum sensors for their specific requirements. Both the state of Baden-Württemberg and the Fraunhofer-Gesellschaft are supporting the four-year project with one million euros each.

The application laboratory is being set up as part of the Fraunhofer lighthouse project »QMag«, short for quantum magnetometry. In this project, researchers...

Im Focus: How Cells Assemble Their Skeleton

Researchers study the formation of microtubules

Microtubules, filamentous structures within the cell, are required for many important processes, including cell division and intracellular transport. A...

Im Focus: World Premiere in Zurich: Machine keeps human livers alive for one week outside of the body

Researchers from the University Hospital Zurich, ETH Zurich, Wyss Zurich and the University of Zurich have developed a machine that repairs injured human livers and keep them alive outside the body for one week. This breakthrough may increase the number of available organs for transplantation saving many lives of patients with severe liver diseases or cancer.

Until now, livers could be stored safely outside the body for only a few hours. With the novel perfusion technology, livers - and even injured livers - can now...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

„Advanced Battery Power“- Conference, Contributions are welcome!

07.01.2020 | Event News

 
Latest News

Molecules move faster on a rough terrain

20.01.2020 | Physics and Astronomy

Spider-Man-style robotic graspers defy gravity

20.01.2020 | Physics and Astronomy

Laser diode emits deep UV light

20.01.2020 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>