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 Decoding cement's shape promises greener concrete
08.12.2016 | Rice University

nachricht Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D
08.12.2016 | DOE/Brookhaven National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>