Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Observing the Unobservable: Researchers Measure Electron Orbitals of Molecules in 3D

05.10.2015

Many of you will remember them from your physics lessons at school: often represented as colourful clouds or balloons, electron orbitals provide information on the whereabouts of the electrons in atoms and molecules. Scientists from the University of Graz, Forschungszentrum Jülich, and the Physikalisch-Technische Bundesanstalt have now succeeded in experimentally recording these structures in all three dimensions. They achieved this by further developing a method they had already applied two years ago to make these orbitals visible in two dimensions. Their findings have now been published in the scientific journal Nature Communications.

In quantum physics, electrons behave both as particles and as waves. The wave nature can be described by the spatial wave function, the orbital. “Orbitals contain information on the spatial distribution of the electrons at a certain energy. If they are known, all the relevant properties of a material can be derived,” explains Prof. Peter Puschnig from the University of Graz.


Photonen schießen Elektronen aus einer Schicht von Molekülen auf einer Silberoberfläche, was die Rekonstruktion von Molekühlorbitalen ermöglich. Foto: Lüftner/Institut für Physik der Uni Graz

However, the laws of quantum mechanics prevent the direct observation of how an electron propagates as a wave. Two years ago, however, scientists from Graz and Jülich for the first time recorded orbitals of larger complex molecules. For their measurements, they used photoelectron spectroscopy, based on the photoelectric effect.

In this procedure, a molecular layer on a silver surface is bombarded with photons (particles of light), causing the energetically excited electrons to be released. “The electrons do not simply fly around in space. Instead, their angular and energy distributions enable us to draw conclusions about the molecular orbitals,” says Puschnig.

By further refining this method, the scientists have now succeeded in reconstructing the orbitals in all three dimensions. This meant that the experiment had to be performed with various photon energies, i.e. different wavelengths of light, in the ultraviolet range. “Additional information on the third dimension can be obtained with variable wavelengths in much the same way as a camera takes repeated pictures of one object with a variable focus,” explains Prof. Stefan Tautz from Forschungszentrum Jülich.

However, it took a long time before it was possible to combine the data gathered in different measurement series into one spatial model. “Until now, we were unable to compare the measured intensities originating from different photon energies,” says Prof. Michael Ramsey from the Department of Physics at the University of Graz. In order to obtain comparable values, the Jülich researchers installed their detector at the Metrology Light Source (MLS) of the Physikalisch-Technische Bundesanstalt (PTB) in Berlin.

“Our synchrotron radiation source is one of the few worldwide that provides a precisely calibrated photon flux,” explains Dr. Alexander Gottwald from PTB. On the basis of the data from the calibrated measurements, the scientists at Graz were then able to reconstruct the electron distributions in three dimensions within the context of the research core are “Models and Simulation”.

The research team from Jülich, Graz, and Berlin was thus able observe the wave function, which according to the rules of quantum mechanics is in fact considered unobservable. The results are long-sought proof of the orbital concept as such. The result is also relevant for physics: “Our experiment provides important new physical insights into the underlying photoelectric effect,” says Stefan Tautz. Somewhat surprisingly, the electrons that are released can be described in a manner very similar to free electrons – an idea that was rejected almost 50 years ago on the basis of the assumed scattering by the atomic cores.

Original publication:
S. Weiß, D. Lüftner, T. Ules, E. M. Reinisch, H. Kaser, A. Gottwald, M. Richter, S. Soubatch, G. Koller, M. G. Ramsey, F. S. Tautz, and P. Puschnig, Exploring three-dimensional orbital imaging with energy dependent photoemission tomography, Nature Communications (2015)

Picture material on request.

Contact:
Assoz.-Prof. Dr. Peter Puschnig
Institute of Physics, University of Graz
Tel.: +43 316 380-5230
E-Mail: peter.puschnig@uni-graz.at

Mag. Gudrun Pichler | Karl-Franzens-Universität Graz
Further information:
http://www.uni-graz.at

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>