Breakthrough in Photoemission Spectroscopy Allows Electronic Investigations Inside Crystals

The physical properties of solid substances are based on electronic states inside the materials. Now, an international team of researchers with the involvement of Jülich scientists has succeeded in studying these states in previously unimagined depths. The results have been published as an advance online publication by Nature Materials. In the "News and Views" commentary, the method is predicted to have a considerable potential for materials research.

For their measurements, the researchers from Germany, the USA, and Japan used the established method of angle-resolved photoemission spectroscopy. However, they used with a light source that was 100-times stronger than usual. This type of light is produced at a mere handful of scientific facilities throughout the world, in Germany, for instance, at the PETRA III storage ring in Hamburg. The team used SPring-8 in Japan, which is currently the world's most powerful synchrotron radiation facility in the hard X-ray range.

Photoemission spectroscopy has been used since the 1970s and is based on the photoelectric effect first theoretically described by Albert Einstein in 1905. Scientists use the method to irradiate samples with light, which causes electrons to become detached from the material. The distribution of angles and energy from the escaping electrons reveals information on the electronic states of the sample, for instance, the position and movement of electrons, band structures, or magnetic properties.

However, this had previously only been achieved for the first approximately five to ten atomic layers at the surfaces. From deeper layers, too few electrons reached the detectors of the measuring instruments. The scientists have now succeeded in achieving a view inside tungsten and arsenide over ten times deeper thanks to the especially brilliant light with high energies of up to six kiloelectron volts, an improved electron spectrometer, and cleverly selected sample material.

The participating scientists at SPring-8 adjusted the light source to allow a maximum number of photons to reach the sample on the smallest possible area. Experimental physicists from Jülich, Erlangen, Mainz, and Berkeley, optimized the spectrometer used and studied sample materials with low lattice vibrations in order to obtain the most detailed results possible. Theoretical physicists from Munich and Davis developed models that can be used to interpret the measurement results.

 

Air Products Announces North America Price Increase for Liquid and Bulk Helium Gases

Effective September 1, 2011, or as contracts permit, Air Products will be implementing a price increase of 15 percent for liquid and bulk helium gases in North America.

The pricing adjustment is the result of several factors including the continued strong demand over the past year for helium and significant reductions in supply. The helium market has been tight across the globe with product allocations implemented by the U.S. Bureau of Land Management and with many other global helium sources producing below capacity. Additionally, new helium sources located primarily outside of the U.S. are extremely expensive, wholesale prices for crude and processed liquid helium have increased, and costs have escalated for power and diesel.

Air Products’ worldwide helium team is managing this difficult situation on a daily basis so that it can continue to bring uninterruptible supply to customers. It is expected that demand will exceed supply for the next two to three years, thus creating ongoing shortages in the market.

 

Locating the elusive

 Researchers at Helmholtz-Zentrum Berlin (HZB) in close collaboration with colleagues in France and UK, have engineered a material that exhibits a rare and versatile trait in magnetism at room temperature. It's called a "multiferroic," and it means that the material has properties allowing it to be both electrically charged (ferroelectric) and also the ability to be magnetic (ferromagnetic), with its magnetisation controlled by electricity.

This research was based around a material known as barium titanate (BaTiO3), a ferroelectric crystal that is promising to have potential uses in multi-state data storage while being cost effective.

"We've shown a way where you can obtain a multiferroic at room temperature," said Sergio Valencia, post doc researcher at HZB, referring to the scarcity of room temperature examples. "Barium titanate is ferromagnetic, so it means you have a net-magnetic moment you can really control by an electric field.

The idea is that you can apply a voltage to the ferroelectric reversing the ferroelectric polarization which in turn affects the magnetization of your film [BaTiO3]. You can use this for example to write bits of information in memories of computers by only applying voltages, which is much cheaper in terms of power than traditionally applying magnetic fields."

It is this ability to control the material's magnetism and to be able to do it at room temperatures which makes this multiferroic potentially more cost-effective compared to other current multiferroic materials, which require complex arrangements to work.

Finding these two traits of ferromagnetic and ferroelectric working together in a compound is tricky due to the strange love-hate relationship exhibited by the two phenomena. What a ferromagnetic requires to exist is not the same as what a ferroelectric requires.

Yet strangely, the two compliment each other and share a strong relationship, where one affects the other. The scarcity of these multiferroics however, is a result of this unique phenomenon combined with the few naturally occurring examples.

"They are scarce and the problem is that most of them are multiferroic only at very low temperatures," added Valencia. "Therefore they are not useful for applications. If you have to go to -270 °C for a multiferroic then it's really complicated and expensive to implement them in room temperature working devices."

The researchers witnessed this multiferroic behaviour by investigating magnetic moments of Titanium (Ti) and Oxygen (O) atoms in BaTiO3 by using synchrotron radiation source BESSY II of Helmholtz-Zentrum Berlin. They used a research method known as soft X-ray resonant magnetic scattering.

The team was able to witness the dual traits of both ferroelectric and ferromagnetic in the thin films of BaTiO3. And since BaTiO3 is a non-magnetic ferroelectric material at room temperature, the ferromagnetism was induced by proximity to natural ferromagnets such as iron (Fe) and Cobalt (Co). In order to achieve these results the researchers deposited a ten atom thin film of iron and cobalt on top of a four atom thin BaTiO3 film. "These small thicknesses are indeed required for the implementation of such materials in devices to keep their small size," added Valencia.

Original publication:
"Interface-induced room-temperature multiferroicity in BaTiO3"; Nature Materials

New tests for dangerous 'legal marijuana,' 'bath salts' and other emerging designer drugs

 Scientists report the development of much needed new tests to help cope with a wave of deaths, emergency room visits and other problems from a new genre of dangerous designer drugs sold legally in stores and online that mimic the effects of cocaine, ecstasy and marijuana.

They spoke at the 242nd National Meeting & Exposition of the American Chemical Society (ACS), being held in Denver.

The reports, among more than 7,500 on the ACS agenda, focus on drugs sold as "bath salts," "plant food," "incense" and other products with colorful names, such as "Ivory Wave," "Red Dove" and "legal marijuana." They provide users with a high, but many have not yet been made illegal and are undetectable with current drug tests. In one presentation on these "legal highs," a United Kingdom researcher reported a new method to trace the source of the substances in "bath salts." In the other, a U.S. researcher discussed the challenges facing law enforcement and policy makers in regulating synthetic versions of marijuana.

Oliver Sutcliffe, Ph.D., and his collaborators reported the successful use of a method called isotope ratio mass spectrometry (IRMS) to determine who is making bath salts -- drugs that can cause euphoria, paranoia, anxiety and hallucinations when snorted, smoked or injected -- and which chemical companies supplied the raw materials. He and his co-workers are based at the University of Strathclyde and the James Hutton Institute in the U.K.

"With the new method, we could work backwards and trace the substances back to the starting materials," said Sutcliffe. IRMS measures the relative amounts of an element's different forms, or isotopic ratio. "This method was successful because the isotopic ratio of the starting material is transferred like a fingerprint through the synthesis," he explained.

"Bath salts" first garnered major media attention in the U.K. in early 2010, and then became a problem in the U.S. These products are not in the supermarket soap aisle -- they are sold on the Internet, on the street and in stores that sell drug paraphernalia. They are sold in small individual bags for as low as $20 each for the real purpose of providing a cheap, legal high.

The powders often contain mephedrone, which is a synthetic compound, structurally related to methcathinone, which is found in Khat -- a plant that is illegal in many countries, including the U.K. and the U.S. Usually, that would mean that these compounds (and derivatives thereof) would be illegal in those countries too, but because the bath salts are labeled "not for human consumption," they get around this restriction and other legislation governing the supply of medicines for human use. However, Florida and Louisiana -- two hotspots of bath salts abuse -- specifically banned the substances. U.K. officials banned the import of bath salts, which may lead some in the drug trade to set up clandestine labs on U.K. soil, said Sutcliffe. The new method provides law enforcement with a tool to track down these bath salts manufacturers.

In previous work, Sutcliffe developed the first pure reference standard for mephedrone, as well as the first reliable liquid chromatography test for the substance, which could be easily run in a typical law enforcement lab. The team is also developing a color-change test kit for mephedrone, which he estimates may be available by the end of the year.

In another presentation, Robert Lantz, Ph.D., from the Rocky Mountain Instrumental Laboratories, described another high that is legal in most of the U.S. -- synthetic cannabinoids marketed as incense, a spice product or "legal marijuana" that give a high similar to marijuana without showing up in conventional drug tests.

"We can detect synthetic cannabinoids with modern analytical chemistry techniques, such as liquid or gas chromatography coupled to mass spectrometry, but these assays are too expensive for the 5,000-10,000 urine samples that most drug testing labs receive each day," said Lantz. Most labs screen for drugs with less expensive antibody assays, but because the structures of these substances are so dissimilar, different antibodies would likely be required for many of them, driving up the cost of a more comprehensive test.

Synthetic cannabinoid abuse rose sharply in 2010, according to U.S. poison control centers, up to 2,863 compared to only 14 in 2009. About 200 synthetic cannabinoids exist, but the U.S. Drug Enforcement Agency (DEA) banned only five of those. A handful of states, such as Washington, Georgia and Colorado, banned five of them, but they are not always the same five that the DEA banned. "The states banned several specific compounds without a particular basis for their choices," Lantz pointed out.

Colorado recently passed a law banning any substance that binds to a cannabinoid receptor in the human body. "The bill was well-intentioned, but technically, the new law not only covers synthetic cannabinoids, but also endocannabinoids, which are naturally occurring substances that the human body produces to regulate many normal processes," said Lantz.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.

Hollywood screenwriters and scientists: More than an artistic collaboration

In this International Year of Chemistry (IYC), writers and producers for the most popular crime and science-related television shows and movies are putting out an all-points bulletin for scientists to advise them on the accuracy of their plots involving lab tests, crime scenes, etc., and to even give them story ideas.

They really do want to get it right, and this is very good news for young people who absorb the information from these shows, and this helps shape their positive career decisions. That's the message delivered in Denver by producers and writers from top television shows speaking at a special Presidential Event at the American Chemical Society's (ACS) 242nd National Meeting & Exposition.

Producers and writers for some of television's most popular medical, crime, science and science fiction shows today said they do strive for accuracy and ask more scientists to get involved and lend a hand in helping TV accurately portray science. They spoke at a symposium entitled "Science on the Hollywood Screen." In addition to CSI, other shows represented were Breaking Bad, CSI New York, Buffy, Battlestar and Torchwood.

"Science on the Hollywood Screen" is one of the meeting's special Presidential Events, and was co-organized by Nancy B. Jackson, Ph.D., ACS President, and Donna Nelson, Ph.D. Nelson, a chemist adviser for the six-time Emmy Award-winning AMC Channel show Breaking Bad, organized the program with Jackson and said Hollywood needs more scientists to volunteer to vet the scientific accuracy of scripts and storyboards.

"CSI is a great example of how a highly popular show can be both entertaining and make science understandable to the public," said Nelson, who is with affiliated with the University of Oklahoma and the Massachusetts Institute of Technology. "The people who make TV shows and films really are interested in presenting science accurately. That's why they have been encouraging scientists like myself to serve as technical advisers. It's been great fun for me and I even have appeared in a cameo role on Breaking Bad."

The producers of this show are serious in striving for accuracy and realism, she said. For example, the credits at the start of Breaking Bad feature symbols of chemical elements from the Periodic Table. The symbols Br and Ba, which stand for the elements bromine and barium, are depicted in the title of the show.

Not only should chemists and other scientists volunteer to advise the staffs of these popular shows, Nelson said, but "we should offer script ideas. The writers and producers are open to this. The more collaboration we in our profession have with these shows and with Hollywood films, the more we can raise the public's awareness about the importance of science." She also contended that the better writers get to know scientists the better equipped they will be to accurately portray them.

With 2011 being the International Year of Chemistry (IYC), Nelson said that chemists have a perfect opportunity to help increase public awareness of chemistry's major role in improving everyday life.

Nelson said that the producers and writers in the symposium will discuss how -- with the help of advisers -- they accurately portray scientists at work and suggested how chemists and other scientists can help with scripts in the future. In addition, the symposium focused on new ideas and evaluated existing ones for better communicating science to the public.

Here are titles of presentations in the "Science on the Hollywood Screen" symposium, with summaries of the presentations:

CSI New York: Science personified. Aaron Thomas, Writer, Producer, CSI New York. For writers who do not have a science background, thorough research is essential. The producers of CSI New York go to great lengths ensuring that the stories they tell are grounded in reality. This includes the science and forensic aspects of the show. They base many of their stories on actual cases. The show has an intelligent and diligent staff of assistants who thoroughly cross-check their ideas with the latest science journals and publications to ensure that they are as accurate as possible with their research. Often, ideas that are pitched for episodes of the show begin with interesting science mysteries.CSI: Entertaining science via methodology and analysis. Corrine Marrinan, Writer, Producer, CSI. Forensic chemistry and materials analysis is the cornerstone of any forensic drama, just as it is considered the strongest physical evidence to be presented in a legal case. Accurately depicting these microscopic events in entertainment is considered one of the greatest challenges in on-screen storytelling. Fortunately, advancements in forensic chemistry have developed in tandem with great advancements in the entertainment technology, special effects and computer-generated images. CSI has mastered the visual expression of forensic chemistry in order to make specialized scientific information more accessible to worldwide audiences.Buffy, Battlestar, Torchwood -- Chemistry vs. Magic on Sci Fi TV. Jane Espenson, writer, producer for a variety of television shows. While writers do at times attempt to include science, including chemistry, they find that magic, which serves many of the same basic functions as science, is often more adaptable. The presentation will describe a scene showing some well-researched chemistry and will include a montage of clips from various episodes that depict uses of magic, especially chemical-type potions. For chemistry to get more screen time, it would be advantageous for it to more closely resemble magic.Breaking Bad: Factual and fabulous. Donna Nelson, Associate Professor of Chemistry, Massachusetts Institute of Technology (MIT) and the University of Oklahoma. The presentation will describe what it is like to be a chemist adviser for Breaking Bad and explain why more chemists should offer their talents to help producers of science-related shows and movies. Today is the perfect time for more scientists to volunteer, as show producers say they are working to create programs that are as accurate as possible.Damn it, Jim (Cameron) -- I'm a screenwriter not a chemist! Ann Merchant, The Science & Entertainment Exchange. The presentation will outline the mission and the history of The Science & Entertainment Exchange and examine some of the realities of the relationship between science and entertainment as a way to explore a "win-win" collaboration. It will cover the origins of The Science & Entertainment Exchange and its expertise in both the entertainment and science communities. It will also describe a "typical" consultation, highlight some of the special events The Exchange has hosted and ground the program objectives in the research on education/entertainment.

More information about the International Year of Chemistry can be found at: http://iyc2011.acs.org/

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.