Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Homegrown Solution for Synchrotron Light Source

02.07.2015

Ames Laboratory physicist develops new technique to study electronic properties

It’s often said that necessity is the mother of invention. Such was the case for Ames Laboratory physicist Adam Kaminski who took the research challenge he was facing and turned it into a new solution that will help advance his research.


Advances in angle-resolved photoemission spectroscopy (ARPES) help scientists at the U.S. Department of Energy's Ames Laboratory study electronic properties of new materials.

Two years ago the National Science Foundation closed the synchrotron in Stoughton, Wisc. More recently, Brookhaven National Lab closed its synchrotron light source to make way for a more advanced and powerful facility. Concerned that this would leave him without the low-energy light source he needed to study the electronic properties of new materials, he improvised, and the result was the development of a new technique that provides a home-grown, laboratory-based solution.

Kaminski uses a technique called angle-resolved photoemission spectroscopy (ARPES) in which light energy (photons) is directed at a sample being studied. The photons cause electrons in the sample to be emitted into a vacuum. An electron analyzer measures the energy and momentum of these electrons, providing details about the electron properties within the material.

Besides using synchrotron beam lines, lasers can provide the input energy needed, but there were problems with the existing technology. High-energy, tunable lasers offered variable phonon energy, but lacked the resolution necessary for good results. Low-energy lasers provided excellent resolution but the fixed photon energy limited their usefulness.

So Kaminski, who admittedly knew little about lasers, set about finding a way to make a low-energy laser that was tunable. In searching the literature, he found that such a tunable laser had been suggested, but had never been used in ARPES systems. The laser used a potassium beryllium fluoroborate (KBBF) crystal to quadruple the frequency of infrared laser converting photons to the required “vacuum ultra-violet (UV)” range.

Obtaining such a crystal wasn’t easy. Kaminski found that the main source for the KBBF crystals, China, had embargoed their export. However, he found a research group at Clemson University that was able to grow him the crystal he needed. He was also able to obtain funding through the DOE Office of Science to build the new system. As an added bonus, the crystal growth and preparation was commercialized by Advanced Photonic Crystals, LLC. This will make them available in U.S. for applications such as UV photo lithography, spectral analysis and defense.

In simple terms, Kaminski’s system uses a pair of lasers, with the first acting as a pump for the second one. The resulting beam consists of very short pulses (one quadrillionth of a second) and very high (400 kW) peak power and is directed into a vacuum chamber that contains lenses, mirrors and the above mentioned “magic” crystal. This process quadruples the energy of the photons. By tuning the wavelength of the second laser and rotating the crystal, one can then tune the energy of the produced UV photons. The beam is then focused at the sample in an ultra-high vacuum chamber and a connected electron analyzer measures the electrons emitted from the sample.

“Development of a laboratory-based solution was really important,” Kaminski said. “Our beam is smaller, photon flux is higher by one or two orders of magnitude, and energy resolution is better by a factor of 5.”

For certain experiments, such as Kaminski’s, that can translate into significantly better data. As illustrated by the graphs (directional), synchrotron results of magnesium diboride show a surface band that curves relatively smoothly. Results from the tunable laser ARPES shows a dramatically enhanced plot with a sharp peak and a slight dip before leveling off.

“Our system has significant advantages,” Kaminski said. “It offers much higher resolution. When a researcher has a sample they want tested, we can usually do it the next day. ”

Kaminski has performed ARPES measurements for a number of research groups at Ames Laboratory as well as researchers at Sandia National Laboratory and Princeton.

“It’s great to have the capability to perform measurements right here in the Lab,” he said, “and it’s busy 24/7!”

This work was supported by the DOE Office of Science.

Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Contact Information
Breehan Gerleman Lucchesi
Communications specialist
breehan@ameslab.gov
Phone: 515-294-9750

Breehan Gerleman Lucchesi | newswise

Further reports about: ARPES Electrons Synchrotron basic research lasers light source measurements photons

More articles from Materials Sciences:

nachricht New gel-like coating beefs up the performance of lithium-sulfur batteries
22.03.2017 | Yale University

nachricht Pulverizing electronic waste is green, clean -- and cold
22.03.2017 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>