Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electrons Get Confused

04.11.2010
HZB researchers may have observed the fastest melting of all time

Scientists from Helmholtz-Zentrum Berlin (HZB) observed exotic be-haviour from beryllium oxide (BeO) when they bombarded it with high-speed heavy ions: After being shot in this way, the electrons in the BeO appeared “confused”, and seemed to completely forget the material properties of their environment.


The K1-XV-line-spectrum of beryllium-oxide. Picture: HZB/Schiwietz

The researchers’ measurements show changes in the electronic structure that can be explained by extremely rapid melting around the firing line of the heavy ions. If this interpre-tation is correct, then this would have to be the fastest melting ever observed. The researchers are publishing their results in Physical Review Letters (DOI: 10.1103/ Phys.Rev.Lett.105, 187603 (2010)).

In his experiments, Prof. Dr. Gregor Schiwietz and his team irradiated a beryllium oxide film with high-speed heavy ions of such strong charge that they possessed maximum smashing power. Unlike most other methods, the energy of the heavy ions was chosen so that they would interact chiefly with their outer valence electrons. As heavy ions penetrate into a material, there are typically two effects that occur immediately around the fired ions: the electrons in the immediate surroundings heat up and the atoms become strongly charged. At this point, Auger electrons are emitted, whose energy levels are measurable and show up in a so-called line spectrum. The line spectrum is characteristic for each different material, and normally changes only slightly upon bombardment with heavy ions.

As a world’s first, the HZB researchers have now bombarded an ion crystal (BeO), which has insulator properties, with very high-speed heavy ions (xenon ions), upon which they demonstrated a hitherto unknown effect: The line spectrum of the Auger electrons changed drastically – it became “washed out”, stretching into higher energies. Together with a team of physicists from Poland, Serbia and Brazil, the researchers observed distinctly metallic signatures from the Auger electrons emitted by the heated BeO material. The Auger electrons appeared to have completely “forgotten” their insulator properties. The researchers see this as clear evidence that the band structure breaks down extremely rapidly when the BeO is bombarded with heavy ions – in less than about 100 femtoseconds (one femtosecond is a millionth of a millionth of a millisecond). This breakdown is triggered by the high electron temperatures of up to 100000 Kelvin. In the long term, however, the material of the otherwise cold solid remains overall intact.

The HZB researchers’ results deliver strong evidence of ultra-fast melting processes around the firing line of the heavy ions. This melting is followed by annealing that deletes all permanent signs of the melting process. Prof. Schiwietz hopes to find other ionic crystals that exhibit the same rapid melting process, but in which the annealing process is suppressed. If any are found, then a conceivable application would be programming at femtosecond speeds.

The Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) operates and develops large scale facilities for research with photons (synchrotron beams) and neutrons. The experimental facilities, some of which are unique, are used annually by more than 2,500 guest researchers from universities and other research organisations worldwide. Above all, HZB is known for the unique sample environments that can be created (high magnetic fields, low temperatures). HZB conducts materials research on themes that especially benefit from and are suited to large scale facilities. Research topics include magnetic materials and functional materials. In the research focus area of solar energy, the development of thin film solar cells is a priority, whilst chemical fuels from sunlight are also a vital research theme. HZB has approx.1,100 employees of whom some 800 work on the Lise-Meitner Campus in Wannsee and 300 on the Wilhelm-Conrad-Röntgen Campus in Adlershof.

HZB is a member of the Helmholtz Association of German Research Centres, the largest scientific organisation in Germany.

Franziska Rott | Helmholtz-Zentrum
Further information:
http://www.helmholtz-berlin.de/

Further reports about: BeO HZB beryllium oxide electrons magnetic field magnetic material

More articles from Materials Sciences:

nachricht Scientists channel graphene to understand filtration and ion transport into cells
11.12.2017 | National Institute of Standards and Technology (NIST)

nachricht Successful Mechanical Testing of Nanowires
07.12.2017 | Helmholtz-Zentrum Geesthacht - Zentrum für Material- und Küstenforschung

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>