Tag Archives: NIST

Getting to know your piezoelectrics

It took me a couple of tries before I could see the butterfly in the neutron scattering image (on the left), which illustrates work undertaken in an attempt to better understand piezoelectrics (found in hard drives, loud speakers, etc.) by researchers at Simon Fraser University (Vancouver area, Canada) and the US National Institute of Standards and Technology.

These two neutron scattering images represent the nanoscale structures of single crystals of PMN and PZT. Because the atoms in PMN deviate slightly from their ideal positions, diffuse scattering results in a distinctive "butterfly" shape quite different from that of PZT, in which the atoms are more regularly spaced. Credit: NIST

These two neutron scattering images represent the nanoscale structures of single crystals of PMN and PZT. Because the atoms in PMN deviate slightly from their ideal positions, diffuse scattering results in a distinctive “butterfly” shape quite different from that of PZT, in which the atoms are more regularly spaced.
Credit: NIST

A Jan. 30, 2014 news release on EurekAlert (also found on on the NIST website where it’s dated Jan. 29, 2014) describes piezoelectrics,

Piezoelectrics—materials that can change mechanical stress to electricity and back again—are everywhere in modern life. Computer hard drives. Loud speakers. Medical ultrasound. Sonar. Though piezoelectrics are a widely used technology, there are major gaps in our understanding of how they work. Now researchers at the National Institute of Standards and Technology (NIST) and Canada’s Simon Fraser University believe they’ve learned why one of the main classes of these materials, known as relaxors, behaves in distinctly different ways from the rest and exhibit the largest piezoelectric effect. And the discovery comes in the shape of a butterfly. …

The news release goes on to explain piezoelectrics and provide details about how the researchers made their discovery,

The team examined two of the most commonly used piezoelectric compounds—the ferroelectric PZT and the relaxor PMN—which look very similar on a microscopic scale. Both are crystalline materials composed of cube-shaped unit cells (the basic building blocks of all crystals) that contain one lead atom and three oxygen atoms. The essential difference is found at the centers of the cells: in PZT these are randomly occupied by either one zirconium atom or one titanium atom, both of which have the same electric charge, but in PMN one finds either niobium or manganese, which have very different electric charges. The differently charged atoms produce strong electric fields that vary randomly from one unit cell to another in PMN and other relaxors, a situation absent in PZT.

“PMN-based relaxors and ferroelectric PZT have been known for decades, but it has been difficult to identify conclusively the origin of the behavioral differences between them because it has been impossible to grow sufficiently large single crystals of PZT,” says the NIST Center for Neutron Research (NCNR)’s Peter Gehring. “We’ve wanted a fundamental explanation of why relaxors exhibit the greatest piezoelectric effect for a long time because this would help guide efforts to optimize this technologically valuable property.”

A few years ago, scientists from Simon Fraser University found a way to make crystals of PZT large enough that PZT and PMN crystals could be examined with a single tool for the first time, permitting the first apples-to-apples comparison of relaxors and ferroelectrics. That tool was the NCNR’s neutron beams, which revealed new details about where the atoms in the unit cells were located. In PZT, the atoms sat more or less right where they were expected, but in the PMN, their locations deviated from their expected positions—a finding Gehring says could explain the essentials of relaxor behavior.

“The neutron beams scatter off the PMN crystals in a shape that resembles a butterfly,” Gehring says. “It gives a characteristic blurriness that reveals the nanoscale structure that exists in PMN—and in all other relaxors studied with this method as well—but does not exist in PZT. It’s our belief that this butterfly-shaped scattering might be a characteristic signature of relaxors.”

Additional tests the team performed showed that PMN-based relaxors are over 100 percent more sensitive to mechanical stimulation compared to PZT, another first-time measurement. Gehring says he hopes the findings will help materials scientists do more to optimize the behavior of piezoelectrics generally.

Here’s a citation for the researchers’ paper,

Role of random electric fields in relaxors by Daniel Phelan, Christopher Stock, Jose A. Rodriguez-Rivera, Songxue Chia, Juscelino Leão, Xifa Long, Yujuan Xie, Alexei A. Bokov, Zuo-Guang Ye, Panchapakesan Ganesh, and Peter M. Gehring. Proceedings of the National Academy of Sciences, Jan. 21, 2014. DOI:10.1073/pnas.1314780111

This paper is behind a paywall.

Casimir and its reins: engineering nanostructures to control quantum effects

Thank you to whomever wrote this headline for the Oct. 22, 2013 US National Institute of Standards and Technology (NIST) news release, also on EurekAlert, titled: The Reins of Casimir: Engineered Nanostructures Could Offer Way to Control Quantum Effect … Once a Mystery Is Solved, for getting the word ‘reins’ correct.

I can no longer hold back my concern over the fact that there are three words that sound the same but have different meanings and one of those words is often mistakenly used in place of the other.

reins

reigns

rains

The first one, reins, refers to narrow leather straps used to control animals (usually horses), as per this picture, It’s also used as a verb to indicate situation where control must be exerted, e.g., the spending must be reined in.

Reining Sliding Stop Mannheim Maimarkt 2007 Date 01.05.2007 Source  Own work Author AllX [downloaded from http://en.wikipedia.org/wiki/File:Reining_slidingstop.jpg]

Reining Sliding Stop Mannheim Maimarkt 2007 Date 01.05.2007 Credit: AllX [downloaded from http://en.wikipedia.org/wiki/File:Reining_slidingstop.jpg]

 This ‘reign’ usually references people like these,

“Queen Elizabeth II greets employees on her walk from NASA’s Goddard Space Flight Center mission control to a reception in the center’s main auditorium in Greenbelt, Maryland where she was presented with a framed Hubble image by Congressman Steny Hoyer and Senator Barbara Mikulski. Queen Elizabeth II and her husband, Prince Philip, Duke of Edinburgh, visited the NASA Goddard Space Flight Center as one of the last stops on their six-day United States visit.” Credit: NASA/Bill Ingalls [downloaded from http://en.wikipedia.org/wiki/File:Elizabeth_II_greets_NASA_GSFC_employees,_May_8,_2007_edit.jpg]

“Queen Elizabeth II greets employees on her walk from NASA’s Goddard Space Flight Center mission control to a reception in the center’s main auditorium in Greenbelt, Maryland where she was presented with a framed Hubble image by Congressman Steny Hoyer and Senator Barbara Mikulski. Queen Elizabeth II and her husband, Prince Philip, Duke of Edinburgh, visited the NASA Goddard Space Flight Center as one of the last stops on their six-day United States visit.” Credit: NASA/Bill Ingalls [downloaded from http://en.wikipedia.org/wiki/File:Elizabeth_II_greets_NASA_GSFC_employees,_May_8,_2007_edit.jpg]

 And,

Thailand's King Bhumibol Adulyadej waves to well-wishers during a concert at Siriraj hospital in Bangkok on September 29, 2010. Credit: Government of Thailand [downloaded from http://en.wikipedia.org/wiki/File:King_Bhumibol_Adulyadej_2010-9-29.jpg]

Thailand’s King Bhumibol Adulyadej waves to well-wishers during a concert at Siriraj hospital in Bangkok on September 29, 2010. Credit: Government of Thailand [downloaded from http://en.wikipedia.org/wiki/File:King_Bhumibol_Adulyadej_2010-9-29.jpg]

Kings, Queens, etc. reign over or rule their subjects or they have reigns, i.e., the period during which they hold the position of queen/king, etc. There are also uses such as this one found in the song title ‘Love Reign O’er Me’ (Pete Townshend)

I’ve lost count of the times I’ve seen ‘reigns’ used in place of ‘reins’, the worst part being? I’ve caught myself making the mistake. So, a heartfelt thank you to the NIST news release writer for getting it right. As for the other ‘rains’, neither I not anyone else seems to make that mistake (so far as I’ve seen).

Now on to the news,

You might think that a pair of parallel plates hanging motionless in a vacuum just a fraction of a micrometer away from each other would be like strangers passing in the night—so close but destined never to meet. Thanks to quantum mechanics, you would be wrong.

Scientists working to engineer nanoscale machines know this only too well as they have to grapple with quantum forces and all the weirdness that comes with them. These quantum forces, most notably the Casimir effect, can play havoc if you need to keep closely spaced surfaces from coming together.

Controlling these effects may also be necessary for making small mechanical parts that never stick to each other, for building certain types of quantum computers, and for studying gravity at the microscale.

In trying to solve the problem of keeping closely spaced surfaces from coming together, the scientists uncovered another problem,

One of the insights of quantum mechanics is that no space, not even outer space, is ever truly empty. It’s full of energy in the form of quantum fluctuations, including fluctuating electromagnetic fields that seemingly come from nowhere and disappear just as fast.

Some of this energy, however, just isn’t able to “fit” in the submicrometer space between a pair of electromechanical contacts. More energy on the outside than on the inside results in a kind of “pressure” called the Casimir force, which can be powerful enough to push the contacts together and stick.

Prevailing theory does a good job describing the Casimir force between featureless, flat surfaces and even between most smoothly curved surfaces. However, according to NIST researcher and co-author of the paper, Vladimir Aksyuk, existing theory fails to predict the interactions they observed in their experiment.

“In our experiment, we measured the Casimir attraction between a gold-coated sphere and flat gold surfaces patterned with rows of periodic, flat-topped ridges, each less than 100 nanometers across, separated by somewhat wider gaps with deep sheer-walled sides,” says Aksyuk. “We wanted to see how a nanostructured metallic surface would affect the Casimir interaction, which had never been attempted with a metal surface before. Naturally, we expected that there would be reduced attraction between our grooved surface and the sphere, regardless of the distance between them, because the top of the grooved surface presents less total surface area and less material. However, we knew the Casimir force’s dependence on the surface shape is not that simple.”

Indeed, what they found was more complicated.

According to Aksyuk, when they increased the separation between the surface of the sphere and the grooved surface, the researchers found that the Casimir attraction decreased much more quickly than expected. When they moved the sphere farther away, the force fell by a factor of two below the theoretically predicted value. When they moved the sphere surface close to the ridge tops, the attraction per unit of ridge top surface area increased.

“Theory can account for the stronger attraction, but not for the too-rapid weakening of the force with increased separation,” says Aksyuk. “So this is new territory, and the physics community is going to need to come up with a new model to describe it.”

For the curious, here’s a link to and a citation for the research paper,

Strong Casimir force reduction through metallic surface nanostructuring by Francesco Intravaia, Stephan Koev, Il Woong Jung, A. Alec Talin, Paul S. Davids, Ricardo S. Decca, Vladimir A. Aksyuk, Diego A. R. Dalvit, & Daniel López. Nature Communications 4, Article number: 2515 doi:10.1038/ncomms3515 Published 27 September 2013.

This article is open access.

Ballooning with carbon nanotubes on behalf of climate science

What a gorgeous picture!

Scientific balloon launched from New Mexico in September 2013 carrying an experimental instrument designed to collect and measure the energy of light emitted by the Sun, with the help of NIST chips coated with carbon nanotubes. Credit: LASP

Scientific balloon launched from New Mexico in September 2013 carrying an experimental instrument designed to collect and measure the energy of light emitted by the Sun, with the help of NIST chips coated with carbon nanotubes.
Credit: LASP

US National Institute of Standards and Technology (NIST) researchers made the carbon nanotube chips which help the instruments in the pictured balloon (above) to collect data about light. From the Oct. 24, 2013 news item on Nanowerk,,

A huge plastic balloon floated high in the skies over New Mexico on Sept. 29, 2013, carrying instruments to collect climate-related test data with the help of carbon nanotube chips made by the National Institute of Standards and Technology (NIST).

The onboard instrument was an experimental spectrometer designed to collect and measure visible and infrared wavelengths of light ranging from 350 to 2,300 nanometers. Simpler, lighter and less expensive than conventional counterparts, the spectrometer was tested to determine how accurately it can measure the relative energy of light emitted by the Sun and subsequently reflected or scattered by the Earth and Moon.

The Oct. 22, 2013 NIST news release, which originated the news item, provides some additional detail (Note: Footnotes have been removed),

Researchers at NIST’s Boulder, Colo., campus made the spectrometer’s “slit,” a high-precision chip that selected the entering light. The device was made under a recent agreement between NIST and the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics (LASP). The slit was then calibrated at NIST’s Gaithersburg, Md., headquarters.

For nearly a decade, NIST Boulder researchers have been using carbon nanotubes, the darkest material on Earth, to make coatings for laser power detectors. Nanotubes efficiently absorb nearly all light across a broad span of wavelengths, a useful feature for reducing internal scatter in the balloon imager. NIST also has facilities for, and expertise in, pairing nanotubes with micromachined silicon chips.

The Oct. 1, 2013 LASP (University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics) news release about the project offers information about the climate change data the researchers are hoping to collect and about the spectrometer being used for that purpose,

The instrument, funded by a $4.7 million NASA Earth Science Technology Office Instrument Incubator Program contract, is intended to acquire extremely accurate radiometric measurements of Earth relative to the incident sunlight. Over time, such measurements can tell scientists about changes in land-use, vegetation, urban landscape use, and atmospheric conditions on our planet. Such long-term radiometric measurements from the HyperSpectral Imager for Climate Science (HySICS) instrument can then help scientists identify the drivers of climate change.

Greg Kopp, HySICS Principal Investigator and CU-LASP research scientist, said, “HySICS allows us to acquire an accurate baseline of current Earth conditions so that we can monitor changes that are so relevant to society. This high altitude balloon flight was the first of two to demonstrate the instrument’s potential space capabilities needed to extend the measurements around the globe and over longer times.”

The instrument relies on precise measurements of the Sun for on-orbit calibrations. These solar measurements provide calibrations of the Earth measurements against this well-measured solar reference that other high accuracy space assets provide. Based on accurate solar calibrations, the HySICS radiometric measurements of the Earth can thus establish a long-term data record that is ten times more accurate than any current measurements.

For anyone interested in a more technical description of the device, the NIST news release has this,

For the balloon spectrometer, known as HySICS (HyperSpectral Imager for Climate Science), NIST made two types of custom chips that were stacked together in a sandwich. In the middle were aperture chips, coated with aluminum to block light transmission through the silicon, with small rectangular openings etched into the chip to allow light into the instrument.

A precision spectrometer must ensure that it only gathers light coming directly from its target, so the two outer layers of the sandwich were masking chips—larger openings etched at an angle and coated with tall, thin carbon nanotubes. These VANTAs (“vertically aligned nanotube arrays”) act as superefficient sponges to absorb scattered or stray light across the entire spectral range of the Sun.

While the balloon was in flight, the spectrometer scanned the slit across the Sun to measure solar irradiance. Spectral filters were calibrated by scanning the slit across the Moon and making measurements with and without filters in the beam path. The spectrometer also imaged light emitted from the Earth using the Sun as a reference light source.

For the information junkies amongst us, the Oct. 22, 2013 NIST news release offers links to more information about carbon nanotubes, etc. while the Oct. 1, 2013 LASP news release offers contact information for lead researcher, Greg Kopp.

‘Entangling’ microscopic drum beats with electrical signals

Scientists at the US National Institute of Standards and Technology (NIST) have gotten closer to extending observations pf quantum entanglement into the macroscale (real life scale) according to an Oct. 3, 2013 news item on Nanowerk,

Extending evidence of quantum behavior farther into the large-scale world of everyday life, physicists at the National Institute of Standards and Technology (NIST) have “entangled” — linked the properties of — a microscopic mechanical drum with electrical signals. The results confirm that NIST’s micro-drum could be used as a quantum memory in future quantum computers, which would harness the rules of quantum physics to solve important problems that are intractable today. The work also marks the first-ever entanglement of a macroscopic oscillator, expanding the range of practical uses of the drum.

The Oct. 3, 2013 NIST news release, which originated the news item, describes how scientists are increasingly observing  and testing for entanglement at larger scales,

Entanglement is a curious feature of the quantum world once believed to occur only at atomic and smaller scales. In recent years, scientists have been finding it in larger systems. Entanglement has technological uses. For instance, it is essential for quantum computing operations such as correcting errors, and for quantum teleportation of data from one place to another.

The experiments, described Oct. 3, 2013, in Science Express,* were performed at JILA, a joint institute of NIST and the University of Colorado Boulder.

NIST introduced the aluminum micro-drum in 2011 and earlier this year suggested it might be able to store data in quantum computers.** The drum—just 15 micrometers in diameter and 100 nanometers thick—features both mechanical properties (such as vibrations) and quantum properties (such as the ability to store and transfer individual quanta of energy).

The drum is part of an electromechanical circuit that can exchange certain quantum states between the waveform of a microwave pulse and vibration in the drum. In the latest JILA experiment, a microwave signal “cooled” the drum to a very low energy level, just one unit of vibration, in a way analogous to some laser-cooling techniques. Then another signal caused the drum’s motion to become entangled with a microwave pulse that emerged spontaneously in the system.

The drum stored the quantum information in the form of vibrational energy for at least 10 microseconds, long enough to be useful in experiments. Then the same type of microwave signal that cooled the drum was used to transfer the state stored in the drum to a second microwave pulse.

Researchers measured the properties of the two microwave pulses—specific points on the curves of the travelling waves—and found that the results were strongly correlated over 10,000 repetitions of the experiment. The evidence of quantum entanglement comes from the fact that measuring the first microwave pulse allowed scientists to anticipate the characteristics of the second pulse with greater accuracy than would otherwise be expected. The correlations between the two pulses indicated that the first pulse was entangled with the drum and the second pulse encoded the drum’s quantum state.

The results suggest that the drum, in addition to its potential as a quantum memory device, also could be used to generate entanglement in microwaves, to convert one form of quantum information to an otherwise incompatible form, and to sense tiny forces with improved precision.

Here are two links to and citations for the researchers’ paper and for an article, respectively,,

* T.A. Palomaki, J.D. Teufel, R.W. Simmonds and K.W. Lehnert. Entangling mechanical motion with microwave fields. Science Express. Oct. 3, 2013. Science DOI: 10.1126/science.1244563
** See 2013 NIST Tech Beat article, “NIST Mechanical Micro-Drum Used as Quantum Memory,” at http://www.nist.gov/pml/div689/drum-031313.cfm.

The Science Express paper is behind a paywall and the NIST Tech Beat article is not avallable due to the US government shutdown.

This ‘entanglement’ news reminds me Geraldo Barbosa’s challenge about seeing quantum entanglement in every day life featured in my Mar. 1, 2012 posting,

You can find Barbosa’s paper/challenge, Can humans see beyond intensity images? here. The abstract presents the challenge this way,

The human’s visual system detect intensity images. Quite interesting, detector systems have shown the existence of different kind of images. Among them, images obtained by two detectors (detector array or spatially scanning detector) capturing signals within short window times may reveal a “hidden” image not contained in either isolated detector: Information on this image depend on the two detectors simultaneously. In general, they are called “high-order” images because they may depend on more than two electric fields. Intensity images depend on the square of magnitude of the light’s electric field. Can the human visual sensory system perceive high-order images as well? This paper proposes a way to test this idea. A positive answer could give new insights on the “visual-conscience” machinery, opening a new sensory channel for humans. Applications could be devised, e.g., head position sensing, privacy in communications at visual ranges and many others.

Blind and visually impaired students introduced to nanotechnology

The US National Institute for Standards and Technology’s (NIST) Center for Nanoscale Science and Technology (CNST) recently held a programme for blind and visually impaired students for the third year. According to a Sept. 20, 2013 news item on Nanowerk,

In July 2013, 45 blind and visually impaired high school students from around the country gathered at Towson University for a weeklong event designed to expose them to science careers long believed to be impossible for the blind. Twenty of those students participated in an exciting educational program on nanoscale science led by NIST Center for Nanoscale Science and Technology (CNST) Project Leader Vladimir Aksyuk, who has participated in this event for the last three years, and CNST/University of Maryland Postdoctoral Researcher Kevin Twedt, who is visually impaired.

The NIST CNST Sept. 19,2012 news release, which originated the news item, offers details about the activities the students engaged in,

During six hours of hands-on activities spread over two days, the students learned the basics of size and scale, the metric system, and received an introduction to the nanoscale. They then learned the techniques scientists use to create and measure nanoscale structures. By probing canes against floor models of different shapes and sizes, they were exposed to how an atomic force microscope probe senses topographic changes on a surface. Using plastic models, they explored the structural relationships between carbon atoms forming either planar graphene or three-dimensional carbon nanotubes. Finally, by scanning a laser pointer across black shapes on white paper and using a photodiode with an audio output that got louder in white regions and quieter in dark regions, the students learned how a scanning electron microscope creates images by scanning a beam of electrons across a surface.

“Most of these students had never really considered careers in science or knew that they are possible for blind people,” says Twedt, who has had 20/200 vision since birth. “In a few days, the students gained an appreciation for the work scientists do and perhaps some will consider going into science later on.”

It’s exciting to see this more inclusive programming.

Touchy feely breakthrough at the nano scale

This first posting back after a three week hiatus (I’m baaack) concerns a study in Sweden where scientists found that people can discern nano wrinkles with their fingertips. From the Sept. 16, 2013 news item on Nanowerk,

In a ground-breaking study, Swedish scientists have shown that people can detect nano-scale wrinkles while running their fingers upon a seemingly smooth surface. The findings could lead such advances as touch screens for the visually impaired and other products, says one of the researchers from KTH Royal Institute of Technology.

The study marks the first time that scientists have quantified how people feel, in terms of a physical property. One of the authors, Mark Rutland, Professor of Surface Chemistry, says that the human finger can discriminate between surfaces patterned with ridges as small as 13 nanometres in amplitude and non-patterned surfaces.

The KTH Sept. 16, 2013 news release by David Callahan, which originated the news item, describes the new understanding of touch and its possible applications,

The study highlights the importance of surface friction and wrinkle wavelength, or wrinkle width – in the tactile perception of fine textures.

When a finger is drawn over a surface, vibrations occur in the finger. People feel these vibrations differently on different structures. The friction properties of the surface control how hard we press on the surface as we explore it. A high friction surface requires us to press less to achieve the optimum friction force.

“This is the breakthrough that allows us to design how things feel and are perceived,” he says. ”It allows, for example, for a certain portion of a touch screen on a smartphone to be designed to feel differently by vibration.”

The research could inform the development of the sense of touch in robotics and virtual reality. A plastic touch screen surface could be made to feel like another material, such as fabric or wood, for example. The findings also enable differentiation in product packaging, or in the products themselves. A shampoo, for example, can be designed to change the feel of one’s hair.

The news release goes on to describe how the research was conducted,

With the collaboration of National Institute of Standards and Technology (NIST) material science labs, Rutland and his colleagues produced 16 chemically-identical surfaces with wrinkle wavelengths (or wrinkle widths) ranging from 300 nanometres to 90 micrometres, and amplitudes (or wrinkle heights) of between seven nanometres and 4.5 micrometres, as well as two non-patterned surfaces. The participants were presented with random pairs of surfaces and asked to run their dominant index finger across each one in a designated direction, which was perpendicular to the groove, before rating the similarity of the two surfaces.

The smallest pattern that could be distinguished from the non-patterned surface had grooves with a wavelength of 760 nanometres and an amplitude of only 13 nanometres.

Rutland says that by bringing together professors and PhD students from two different disciplines – surface chemistry and psychology – the team succeeded in creating “a truly psycho-physical study.”

“The important thing is that touch was previously the unknown sense,” Rutland says. “To make the analogy with vision, it is as if we have just revealed how we perceive colour.

“Now we can start using this knowledge for tactile aesthetics in the same way that colours and intensity can be combined for visual aesthetics.”

Here’s a citation for and link to the researchers’ study,

Feeling Small: Exploring the Tactile Perception Limits by Lisa Skedung, Martin Arvidsson, Jun Young Chung, Christopher M. Stafford, Birgitta Berglund & Mark W. Rutland. Scientific Reports 3, Article number: 2617 doi: 10.1038/srep02617 Published 12 September 2013

This paper is open access.

‘Facebook for molecules’ tackles linguistic issues

As the amount of information about chemicals and molecules continues to explode, scientists at the US National Institute of Standards and Technology (NIST) have devised a type of ‘Facebook for molecules’ which should make the process of searching through the data much easier according to a July 18, 2013 news item on ScienceDaily,

Social media has expanded to reach an unlikely new target: molecules. Scientists at the National Institute of Standards and Technology (NIST) have created networks of molecular data similar to Facebook’s recently debuted graph search feature. While graph search would allow Facebook users to find all their New York-living, beer-drinking buddies in one quick search, the NIST-designed networks could help scientists rapidly sift through enormous chemical and biological data sets to find substances with specific properties, for example all 5-ring chemicals with an affinity for enzyme A. The search approach could help speed up the development of new drugs and designer materials.

There are vocabulary issues associated with creating a search function (from the news item),

Molecules don’t maintain their own online profiles, so a key challenge for the NIST research team was to develop a standard language for scientists to describe their research subjects. For example, one research group may describe a material’s properties as glassy while another team might use the word vitreous, even though the two words have the same meaning, explained Ursula Kattner, a researcher in the Materials Science and Engineering Division at NIST.

One approach to the problem could be to define a standard set of words, but NIST scientists opted for a more flexible approach that could evolve with time. The search language they developed is similar to Indo-European languages like Sanskrit and Latin, which use short roots to build words based on a set of rules, said Talapady Bhat, a research chemist at NIST who has been leading the effort to develop a shared vocabulary for NIST’s scientific databases. He gives the example of the Sanskrit word “yoga,” which is based on the roots “Y(uj),” which means to join, “O,” which means creator, God, or brain, and “Ga,” which means motion or initiation. Similarly, scientists could take the three simple root words “red,” “laser,” and “light,” and combine them into a single compound word “red-laser-light” that conveys a new concept. Using the root and rule-based approach will mean that scientists who know the roots can figure out the meaning of unfamiliar terms, and it also gives scientists flexibility to develop easily understandable new terms in the future.

The NIST team has already applied their root-based vocabulary rules to the chemical structures in PubChem, a “monstrous database” of millions of compounds and chemical substances, to the world wide protein data bank (PDB), and to specific NIST-based databases, said John Elliot, a biophysicist and another member of the team. While the scientific databases haven’t reached a Facebook-like level of more than a billion users, they are actively used by many scientists in the NIST community and beyond.

You can read more about the issues associated with getting precise search results on ScienceDaily and you may be able to access an abstract of the researchers’ (Talapady Bhat , John Elliott, Carelyn Campbell, Ursula Kattner, Shir Boger, Anne Plant)  Challenges and Solutions for Enabling Facebook like Graph-search on Small and Macro-molecular Structural Data presentation (I keep getting an error) which was given at the 2013 American Crystallographic Association (ACA) meeting.

Better photolithography and nanoscale manipulation and manufacturing (maybe) with flat lenses

A flat spray-on lens sounded only mildly intriguing as per the May 23, 2012 University of British Columbia news release (UBC engineer helps pioneer flat spray-on optical lens) on EurekAlert. It was the May 24, 2013 news item on ScienceDaily that provided more exciting possibilities,

For the first time, scientists working at the National Institute of Standards and Technology (NIST) have demonstrated a new type of lens that bends and focuses ultraviolet (UV) light in such an unusual way that it can create ghostly, 3D images of objects that float in free space. The easy-to-build lens could lead to improved photolithography, nanoscale manipulation and manufacturing, and even high-resolution three-dimensional imaging, as well as a number of as-yet-unimagined applications in a diverse range of fields.

The May 24, 2013 NIST news release, which originated the news item, describes some of the optical principles at work,

An article published in the journal Nature* explains that the new lens is formed from a flat slab of metamaterial with special characteristics that cause light to flow backward—a counterintuitive situation in which waves and energy travel in opposite directions, creating a negative refractive index.

Naturally occurring materials such as air or water have a positive refractive index. You can see this when you put a straw into a glass of water and look at it from the side. The straw appears bent and broken as a result of the change in index of refraction between air, which has an index of 1, and water, which has an index of about 1.33. Because the refractive indices are both positive, the portion of the straw immersed in the water appears bent forward with respect to the portion in air.

The negative refractive index of metamaterials causes light entering or exiting the material to bend in a direction opposite what would occur in almost all other materials. For instance, if we looked at our straw placed in a glass filled with a negative-index material, the immersed portion would appear to bend backward, completely unlike the way we’re used to light behaving.

In 1967, Russian physicist Victor Veselago described how a material with both negative electric permittivity and negative magnetic permeability would have a negative index of refraction. (Permittivity is a measure of a material’s response to an applied electric field, while permeability is a measure of the material’s response to an applied magnetic field.)

Veselago reasoned that a material with a refractive index of -1 could be used to make a lens that is flat, as opposed to traditional refractive lenses, which are curved. A flat lens with a refractive index of -1 could be used to directly image three-dimensional objects, projecting a three-dimensional replica into free space.

A negative-index flat lens like this has also been predicted to enable the transfer of image details substantially smaller than the wavelength of light and create higher-resolution images than are possible with lenses made of positive-index materials such as glass.

It seems the metamateriels that solve the problem posed by lenses made of glass present a few problems of their own (from the NIST news release),

… For the past decade, scientists have made metamaterials that work at microwave, infrared and visible wavelengths by fabricating repeating metallic patterns on flat substrates. However, the smaller the wavelength of light scientists want to manipulate, the smaller these features need to be, which makes fabricating the structures an increasingly difficult task. Until now, making metamaterials that work in the UV has been impossible because it required making structures with features as small as 10 nanometers, or 10 billionths of a meter.

Moreover, because of limitations inherent in their design, metamaterials of this type designed for infrared and visible wavelengths have, so far, been shown to impart a negative index of refraction to light that is traveling only in a certain direction, making them hard to use for imaging and other applications that rely on refracted light.

To overcome these problems, researchers working at NIST took inspiration from a theoretical metamaterial design recently proposed by a group at the FOM Institute for Atomic and Molecular Physics in Holland. They adapted the design to work in the UV—a frequency range of particular technological interest.

According to co-authors Xu, Amit Agrawal and Henri Lezec, aside from achieving record-short wavelengths, their metamaterial lens is inherently easy to fabricate. It doesn’t rely on nanoscale patterns, but instead is a simple sandwich of alternating nanometer-thick layers of silver and titanium dioxide, the construction of which is routine. And because its unique design consists of a stack of strongly coupled waveguides sustaining backward waves, the metamaterial exhibits a negative index of refraction to incoming light regardless of its angle of travel.

This realization of a Veselago flat lens operating in the UV is the first such demonstration of a flat lens at any frequency beyond the microwave. By using other combinations of materials, it may be possible to make similarly layered metamaterials for use in other parts of the spectrum, including the visible and the infrared.

The metamaterial flat lens achieves its refractive action over a distance of about two wavelengths of UV light, about half a millionth of a meter—a focal length challenging to achieve with conventional refractive optics such as glass lenses. Furthermore, transmission through the metamaterial can be turned on and off using higher frequency light as a switch, allowing the flat lens to also act as a shutter with no moving parts.

“Our lens will offer other researchers greater flexibility for manipulating UV light at small length scales,” says Lezec. “With its high photon energies, UV light has a myriad of applications, including photochemistry, fluorescence microscopy and semiconductor manufacturing. That, and the fact that our lens is so easy to make, should encourage other researchers to explore its possibilities.”

I would have offered some information about what they are spraying onto the lens but neither the NIST nor the University of British Columbia (UBC) news releases provides any details about the ‘spray-on’ aspect of this flat lens. There is this from the UBC news release,

“The idea of a flat lens goes way back to the 1960s when a Russian physicist came up with the theory,” Chau [Kenneth Chau, an assistant professor in the School of Engineering at UBC's Okanagan campus] says. “The challenge is that there are no naturally occurring materials to make that type of flat lens. Through trial and error, and years of research, we have come up with a fairly simple recipe for a spray-on material that can act as that flat lens.”

The research team has developed a substance that can be affixed to surfaces like a glass slide and turn them into flat lenses for ultraviolet light imaging of biological specimens.

“Curved lenses always have a limited aperture,” he explains. “With a flat lens, suddenly you can make lenses with an arbitrary aperture size – perhaps as big as a football field.”

While the spray-on, flat lens represents a significant advancement in technology, it is only an important first step, Chau says.

“This is the closest validation we have of the original flat lens theory,” he says. “The recipe, now that we’ve got it working, is simple and cost-effective.

For those who want to pursue the research paper, here’s a link to and a citation for it,

All-angle negative refraction and active flat lensing of ultraviolet light by Ting Xu, Amit Agrawal, Maxim Abashin, Kenneth J. Chau, & Henri J. Lezec. Nature 497, 470–474 (23 May 2013) doi:10.1038/nature12158  Published online 22 May 2013

The paper is behind a paywall.

Rice U and the US National Institute of Standards and Technology settle into armchairs, the carbon nanotube kind

An armchair carbon nanotube is amongst the most desirable of carbon nanotubes. You’ll have to look carefully to see the resemblance to an armchair,

Armchair carbon nanotubes, so named for the arrangement of atoms that make their ends look like armchairs, are the most desirable among nanotube researchers for their superior electrical properties. Image by Erik Hároz [downloaded from http://news.rice.edu/2013/02/05/essential-armchair-reading-for-nanotube-researchers-2/]

Armchair carbon nanotubes, so named for the arrangement of atoms that make their ends look like armchairs, are the most desirable among nanotube researchers for their superior electrical properties. Image by Erik Hároz [downloaded from http://news.rice.edu/2013/02/05/essential-armchair-reading-for-nanotube-researchers-2/]

The Feb. 6, 2013 news item on phys.org about the armchair carbon nanotubes notes that this latest research is an early outcome from a recently announced (Oct. 2012) partnership between Rice University and the US National Institute of Standards and Technology (NIST). Trom the news item (Note: Links have been removed),

The first fruits of a cooperative venture between scientists at Rice University and the National Institute of Standards and Technology (NIST) have appeared in a paper that brings together a wealth of information for those who wish to use the unique properties of metallic carbon nanotubes.

The feature article published recently in the Royal Society of Chemistry journal Nanoscale gathers research about the separation and fundamental characteristics of armchair carbon nanotubes, which have been of particular interest to researchers trying to tune their electronic and optical properties.

The Rice University Feb. 5, 2013 news release by Mike Williams, which originated the news item, describe s the process the scientists undertook,

This paper, said Rice physicist Junichiro Kono, provides scientists a valuable resource for detailed information about metallic carbon nanotubes, especially armchair nanotubes. “Basically, we summarized all our recent findings as well as all information we could find in the literature about metallic nanotubes, along with detailed accounts of preparation methods for metal-enriched nanotube samples, to show the community just how much we now understand about these one-dimensional metals,” he said.

As part of the lengthy work, the team compiled and published tables of essential statistics, including optical properties, for a variety of metallic nanotubes. “We provide fundamental theoretical backgrounds and then show very detailed experimental results on unique properties of metallic nanotubes,” Kono said. “This paper summarizes what kind of aspects are understood, and what is not, about fundamental optical processes in nanotubes and will make it easier for researchers to identify their spectroscopic features and transition energies.”

For this of us who are less well versed on armchair carbon nanotubes and their electronic and optical properties, the news releases provides some information (Note: Links have been removed),

Nanotubes come in many flavors, depending on their chirality. Chirality is a characteristic akin to the angles at which a flat sheet of paper might align when wrapped into a tube. Cut the tube in half and the atoms at the open edge would line up in the shape of an armchair, a zigzag or some variant. Even though their raw material is identical – chicken-wire-like hexagons of carbon – the chirality makes all the difference in how nanotubes transmit electricity.

Armchairs are the most coveted because they have no band gap; electrons flow through without resistance. Cables made with armchair nanotubes have the potential to move electricity over great distances with virtually no loss. That makes them the gold standard as the basic element of armchair quantum wire. The ongoing development of this very strong, lightweight, high-capacity cable could improve further the record properties of multifunctional carbon nanotube fibers that are being developed by the group of Rice Professor Matteo Pasquali.

For the project-specific work the scientists performed (Note: Links have been removed),

The new work led by Kono and Robert Hauge, a distinguished faculty fellow in chemistry at Rice, along with scientists at NIST and Los Alamos National Laboratory, looks beyond the armchair’s established electrical properties to further detail their potential for electronic, sensing, optical and photonic devices.

“Of course, to get there, we need really good samples,” Kono said. “Many applications will rely on our ability to separate carbon nanotubes and then assemble macroscopically ordered structures consisting of single-chirality nanotubes. Nobody can do that at this point.”

When a batch of nanotubes comes out of a furnace, it’s a jumble of types. That makes detailed analysis of their characteristics — let alone their practical use — a challenge.

But techniques developed in recent years at Rice and by NIST scientist Ming Zheng to purify metallic nanotubes are beginning to change that. Rice graduate student Erik Hároz said recent experiments established “unambiguous evidence” that a process he and Kono are using called density gradient ultracentrifugation can enrich ensemble samples of armchairs. Taking things further, Zheng’s method of DNA-based ion-exchange chromatography provides very small samples of ultrapure armchair nanotubes of a single chirality.

You can read more about the work at phys.org or at Rice University using the links already provided. For those who’d like to read the research,

Fundamental optical processes in armchair carbon nanotubes by Erik H. Hároz ,  Juan G. Duque,  Xiaomin Tu ,  Ming Zheng ,  Angela R. Hight Walker ,  Robert H. Hauge ,  Stephen K. Doorn and Junichiro Kono. Nanoscale, 2013,5, 1411-1439 DOI: 10.1039/C2NR32769D First published on the web 04 Jan 2013

This article is behind a paywall of sorts.  RSC (Royal Society of Chemistry) Publishing (which publishes Nanoscale) has an open access policy but there are various options, from the RSC Publishing’s Open Access Policy webpage,

RSC Open Access statement

Open Access is the term given to making electronic versions of articles accessible to readers, without any subscription or ‘access side’ fees.

RSC supports Open Access models which seek to ensure that scholarly publishing activities operate in a long term sustainable way.

  • Our fundamental goal is to advance the chemical sciences, through the effective dissemination of high quality research content
  • We seek to maximise the dissemination of the research that we publish
  • We support any and all sustainable and fair models of access. We believe that the integrity and archiving of scholarly content must be maintained throughout
  • We support ‘Gold’* Open Access and encourage funding to be made available to support authors during any transition from reader to author side payments
  • We support the author’s ability to choose where they publish their work to the benefit of the advancement of science. We do not wish authors to be discriminated against if they are unable to pay author-side fees
  • We seek to work closely with other parties, including funders and government agencies, to achieve the above goals

RSC Publishing provides authors with the option to make their article Open Access, through payment of a fee on acceptance. Authors following the traditional route still have deposition options – details are on the ‘Deposition and Licence to Publish’ page of the website.

*There are several types of Open Access:

  • Gold Open Access: Publication costs are covered by an ‘Article Processing Fees’ being paid by authors upon acceptance. The final ‘article of record’ is made available to all, immediately, without any barriers to access
  • Green Open Access: A version of the paper (often the author’s manuscript) is made available via a subject or institutional repository. An embargo period is often involved, typically 6-24 months. No payment is made, and publishers should strive to recoup their investment through traditional sales during the embargo period
  • Delayed Open Access: The final version of the paper is made available by the publisher after an embargo period (e.g. publisher deposit the paper in PubMed after 12 months)

It would seem the option for this article is ‘Delayed Open Access’.