Eric Sembrat's Test Bonanza

The Nobel Prize in Physics 2011 was awarded "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae" with one half to Saul Perlmutter and the other half jointly to Brian P. Schmidt and Adam G. Riess.

The Royal Swedish Academy of Sciences said American Saul Perlmutter would share the 10 million kronor ($1.5 million) award with U.S.-Australian Brian Schmidt and U.S. scientist Adam Riess. Working in two separate research teams during the 1990s -- Perlmutter in one and Schmidt and Riess in the other -- the scientists raced to map the universe's expansion by analyzing a particular type of supernovas, or exploding stars.

Congratulations to Emeritus Professor Eugene Patronis on receiving the 2011 Fellowship award from the Audio Engineering Society!

The Fellowship Award is given to a member who had rendered conspicuous service or is recognized to have made a valuable contribution to the advancement in or dissemination of knowledge of audio engineering or in the promotion of its application in practice.

He is now Professor Emeritus of Physics at the Georgia Institute of Technology where he taught and performed research for fifty-one years. During his teaching career he founded programs in applied physics in the areas of acoustics, electronic instrumentation, and computer interfacing. In addition to numerous refereed scientific publications dealing with nuclear physics, electronics, acoustics, and audio, he has authored chapters in five reference handbooks dealing with nuclear physics, electronics, and audio engineering.

IceCube is gigantic detector, about 400 times the volume of the great pyramid of Giza, that operates at the geographic South Pole. By finding and studying ghost-like neutrino particles, IceCube will open a new window into the Universe and may solve the century-old question of the origin of cosmic rays. Ignacio's talk will describe the operation of IceCube, life at the South Pole, what neutrinos and cosmic rays are and how IceCube uses neutrinos to study the cosmos.

For more information see the Atlanta Science Tavern page.

Regents’ Professor Walter de Heer is recognized for his invention of graphene based electronics –“Carbon Based Solutions for Urban Life” in Shanghai / Wiesbaden on July 29, 2011.

SGL Group—The Carbon Company has awarded the Utz-Hellmuth Felcht Award for the first time at the International Carbon Conference in Shanghai. This prestigious donation of €20,000 will be awarded by SGL Group every two years in honor of its former Supervisory Board Chairman Prof. Utz-Hellmuth Felcht. Honored will be outstanding scientific and technological contributions in the field of carbon and ceramic materials.

The first winner of the Felcht Award is Professor Walter de Heer from the Georgia Institute of Technology in Atlanta, Georgia for his merits in the area of graphene research and his revolutionary concept of graphene based nanoelectronics.

Dr. Gerd Wingefeld, member of the Board of Management of SGL Group, responsible for Technology and Innovation: “The challenges of our time are global: Energy production from alternative sources, energy storage and energy efficiency. Carbon in its various forms and applications can contribute mastering these challenges. Through his work on electronic transportation mechanisms in graphene, Prof. Walter de Heer opened the door to a new era of extremely small electronic circuits.”

Individual graphite layers are known as graphene. In 2010, Konstantin Novoselov and Andre Geim were awarded with the Nobel Prize in Physics for their contributions in the field of electrical properties of the thinnest graphite layers. Graphene has the potential to replace silicon in electronics for applications such as ultra-high frequency electronics. At the time, SGL Group presented its “Carbon Based Solutions for Urban Life” concept, which focuses on innovative applications and sustainable solutions through the use of carbon-based products – from electromobility to lightweight solutions, energy efficient infrastructures and cooling systems in buildings.

In general, the Award will honor a single scientific and technological contribution which provided recent impact of significance on manufacturing and application or has the character of a breakthrough in science.

The Utz-Hellmuth Felcht Award will be presented biennially on the occasion of the International Carbon Conferences held alternately in Asia, Europe, and the USA.  The selection of the awardees is dedicated to an International Award Committee composed of six renowned scientists and persons of high standing in industry.

Assistant Professor Daniel Goldman and his group integrated biological experiment, empirical theory, numerical simulation and a physical model to reveal principles of undulatory locomotion in granular media. High-speed X-ray imaging of the sandfish lizard showed that it swims within the medium without using its limbs by propagating a single-period travelling sinusoidal wave down its body. Using these models and analytical solutions of the RFT, they varied the ratio of undulation amplitude to wavelength (A/λ) and demonstrate an optimal condition for sand-swimming, which for a given A results from the competition between η and λ.  J. R. Soc. Interface, September 7, 2011 8:1332-1345.

Using a technique known as thermochemical nanolithography (TCNL), researchers have developed a new way to fabricate nanometer-scale ferroelectric structures directly on flexible plastic substrates that would be unable to withstand the processing temperatures normally required to create such nanostructures.

The technique, which uses a heated atomic force microscope (AFM) tip to produce patterns, could facilitate high-density, low-cost production of complex ferroelectric structures for energy harvesting arrays, sensors and actuators in nano-electromechanical systems (NEMS) and micro-electromechanical systems (MEMS). The research was reported July 15 in the journal Advanced Materials.

"We can directly create piezoelectric materials of the shape we want, where we want them, on flexible substrates for use in energy harvesting and other applications," said Nazanin Bassiri-Gharb, co-author of the paper and an assistant professor in the School of Mechanical Engineering at the Georgia Institute of Technology. "This is the first time that structures like these have been directly grown with a CMOS-compatible process at such a small resolution. Not only have we been able to grow these ferroelectric structures at low substrate temperatures, but we have also been able to pattern them at very small scales."

The research was sponsored by the National Science Foundation and the U.S. Department of Energy. In addition to the Georgia Tech researchers, the work also involved scientists from the University of Illinois Urbana-Champaign and the University of Nebraska Lincoln.

The researchers have produced wires approximately 30 nanometers wide and spheres with diameters of approximately 10 nanometers using the patterning technique. Spheres with potential application as ferroelectric memory were fabricated at densities exceeding 200 gigabytes per square inch -- currently the record for this perovskite-type ferroelectric material, said Suenne Kim, the paper's first author and a postdoctoral fellow in laboratory of Professor Elisa Riedo in Georgia Tech's School of Physics.

To read the full article, please visit this site:  http://www.gatech.edu/newsroom/release.html?nid=68848

Scientists have discovered a method to control the gas-phase selective catalytic combustion of methane, so finely that if done at room temperature the reaction produces ethylene, while at lower temperatures it yields formaldehyde. The process involves using gold dimer cations as catalysts — that is, positively charged diatomic gold clusters. Being able to catalyze these reactions, at or below room temperature,  may lead to significant cost savings in the synthesis of plastics, synthetic fuels and other  materials. The research was conducted by scientists at the Georgia Institute of Technology and the University of Ulm. It appears in the April 14, 2011, edition of The Journal of Physical Chemistry C.

“_­The beauty of this process is that it allows us to selectively control the products of this catalytic system, so that if one wishes to create formaldehyde, and potentially methyl alcohol, one burns methane by tuning its reaction with oxygen to run at  lower temperatures, but if it’s ethylene  one is after,  the reaction can be tuned to run at room temperature,” said Uzi Landman, Regents’ and Institute Professor of Physics and director of the Center for Computational Materials Science at Georgia Tech.

Full article can be found here.

Scientists have discovered fundamental steps of charging of nano-sized water droplets and unveiled the long-sought-after mechanism of hydrogen emission from irradiated water. Working together at the Georgia Institute of Technology and Tel Aviv University, scientists have discovered when the number of water molecules in a cluster exceeds 83, two excess electrons may attach to it — forming dielectrons — making it a doubly negatively charged nano droplet. Furthermore, the scientists found experimental and theoretical evidence that in droplets comprised of 105 molecules or more, the excess dielectrons participate in a water-splitting process resulting in the liberation of molecular hydrogen and formation of two solvated hydroxide anions.  The results appear in the June 30 issue of the Journal of Physical Chemistry A.

For the full article, please visit this site.

Scientists have discovered fundamental steps of charging of
nano-sized water droplets and unveiled the long-sought-after mechanism of
hydrogen emission from irradiated water. Working together at the Georgia
Institute of Technology and Tel Aviv University, scientists have discovered
when the number of water molecules in a cluster exceeds 83, two excess
electrons may attach to it —
forming dielectrons — making it
a doubly negatively charged nano droplet. Furthermore, the scientists found
experimental and theoretical evidence that in droplets comprised of 105
molecules or more, the excess dielectrons participate in a water-splitting
process resulting in the liberation of molecular hydrogen and formation of two
solvated hydroxide anions.  The
results appear in the June 30 issue of the Journal of Physical Chemistry A.

It has been known since the early 1980s that while single
electrons may attach to small water clusters containing as few as two molecules,
only much larger clusters may attach more than single electrons. Size-selected,
multiple-electron, negatively-charged water clusters have not been observed — until now.

Understanding the nature of excess electrons in water has captured
the attention of scientists for more than half a century, and the hydrated
electrons are known to appear as important reagents in charge-induced aqueous
reactions and molecular biological processes.  Moreover, since the discovery in the early 1960s that the
exposure of water to ionizing radiation causes the emission of gaseous molecular
hydrogen, scientists have been puzzled by the mechanism underlying this
process.  After all, the bonds in
the water molecules that hold the hydrogen atoms to the oxygen atoms are very
strong. The dielectron hydrogen-evolution 
(DEHE) reaction, which produces hydrogen gas and hydroxide anions, may
play a role in radiation-induced reactions with oxidized DNA that have been
shown to underlie mutagenesis, cancer and other diseases.

“The attachment of multiple electrons
to water droplets is controlled by a fine balancing act between the forces that
bind the electrons to the polar water molecules and the strong repulsion
between the negatively charged electrons,” said Uzi Landman, Regents’ and
Institute Professor of Physics, F.E. Callaway Chair and director of the Center
for Computational Materials Science (CCMS) at Georgia Tech.

“Additionally, the binding of an
electron to the cluster disturbs the equilibrium arrangements between the
hydrogen-bonded water molecules and this too has to be counterbalanced by the
attractive binding forces.  To
calculate the pattern and strength of single and two-electron charging of
nano-size water droplets, we developed and employed first-principles quantum mechanical
molecular dynamics simulations that go well beyond any ones that have been used
in this field,” he added. 

Investigations on controlled size-selected clusters allow
explorations of intrinsic properties of finite-sized material aggregates, as
well as probing of the size-dependent evolution of materials properties from
the molecular nano-scale to the condensed phase regime.

In the 1980s Landman, together
with senior research scientists in the CCMS Robert Barnett, the late Charles
Cleveland and Joshua Jortner, professor of chemistry at Tel Aviv University,
discovered that there are two ways that single excess electrons can attach to
water clusters – one in which they bind to the surface of the water droplet,
and the other where they localize in a cavity in the interior of the droplet,
as in the case of bulk water. Subsequently, Landman, Barnett and graduate
student Harri-Pekka Kaukonen reported in 1992 on theoretical investigations
concerning the attachment of two excess electrons to water clusters. They
predicted that such double charging would occur only for sufficiently large nano-droplets.
They also commented on the possible hydrogen evolution reaction. No other work
on dielectron charging of water droplets has followed since.

That is until recently, when Landman, now one of the world leaders in the area of cluster and nano
science, and Barnett teamed up with Ori Chesnovsky, professor of
chemistry, and research associate Rina Giniger at Tel
Aviv University, in a joint project aimed at understanding the process
of dielectron charging of water clusters and the mechanism of the ensuing
reaction - which has not been observed previously in experiments on water
droplets. Using large-scale, state-of-the-art
first-principles dynamic simulations, developed at the CCMS, with all valence
and excess electrons treated quantum mechanically and equipped with a newly
constructed high-resolution time-of-flight mass spectrometer, the researchers
unveiled the intricate physical processes that govern the fundamental dielectron
charging processes of microscopic water droplets and the detailed mechanism of
the water-splitting reaction induced by double charging.

The mass
spectrometric measurements, performed at Tel Aviv, revealed that singly charged
clusters were formed in the size range of six to more than a couple of hundred
water molecules. However, for clusters containing more than a critical size of
83 molecules, doubly charged clusters with two attached excess electrons were
detected for the first time. Most significantly, for clusters with 105 or more
water molecules, the mass spectra provided direct evidence for the loss of a
single hydrogen molecule from the doubly charged clusters.

The theoretical
analysis demonstrated two dominant attachment modes of dielectrons to water
clusters. The first is a surface mode (SS’), where the two repelling electrons
reside in antipodal sites on the surface of the cluster (see the two wave
functions, depicted in green and blue, in Figure 1). The second is another
attachment mode with both electrons occupying a wave function localized in a
hydration cavity in the interior of the cluster — the so-called II binding mode
(see wave function depicted in pink in Figure 2). While both dielectron
attachment modes may be found for clusters with 105 molecules and larger ones,
only the SS’ mode is stable for doubly charged smaller clusters.

“Moreover, starting
from the II, internal cavity attachment mode in a cluster comprised of 105
water molecules, our quantum dynamical simulations showed that the concerted
approach of two protons from two neighboring water molecules located on the
first shell of the internal hydration cavity, leads, in association with the
cavity-localized excess dielectron (see Figure 2), to the formation of a
hydrogen molecule. The two remnant hydroxide anions diffuse away via a sequence
of proton shuttle processes, ultimately solvating near the surface region of
the cluster, while the hydrogen molecule evaporates,” said Landman.

“What’s more, in
addition to uncovering the microscopic reaction pathway, the mechanism which we
discovered requires initial proximity of the two reacting water molecules and
the excess dielectron. This can happen only for the II internal cavity
attachment mode. Consequently, the theory predicts, in agreement with the
experiments, that the reaction would be impeded in clusters with less than 105
molecules where the II mode is energetically highly improbable. Now, that’s a
nice consistency check on the theory,” he added.

As for future plans,
Landman remarked, “While I believe that our work sets methodological and
conceptual benchmarks for studies in this area, there is a lot left to be done.
For example, while our calculated values for the excess single electron
detachment energies are found to be in quantitative agreement with
photoelectron measurements in a broad range of water cluster sizes — containing
from 15 to 105 molecules — providing a consistent interpretation of these
measurements, we would like to obtain experimental data on excess dielectron
detachment energies to compare with our predicted values,” he said.

“Additionally, we
would like to know more about the effects of preparation conditions on the
properties of multiply charged water clusters. We also need to understand the
temperature dependence of the dielectron attachment modes, the influence of
metal impurities, and possibly get data from time-resolved measurements. The understanding
that we gained in this experiment about charge-induced water splitting may
guide our research into artificial photosynthetic systems, as well as the
mechanisms of certain bio-molecular processes and perhaps some atmospheric phenomena.”

“You know,” he added. “We started
working on excess electrons in water clusters quite early, in the 1980s — close
to 25 years ago. If we are to make future progress in this area, it will have
to happen faster than that.”

This research was funded by the U.S. Office of Basic Energy Sciences and the Israel Science Foundation.

Deirdre Shoemaker has become accustomed to people not believing in black holes — even one of her stepson’s teachers.     

“When he was in elementary school, my stepson came home with an English writing assignment on myths,” said the astrophysicist who is an associate professor in the School of Physics and works within the Center for Relativistic Astrophysics. “His topic choices included Big Foot, the Loch Ness monster and black holes.”

Another common misconception that Shoemaker has encountered is that black holes are giant, cosmic vacuum cleaners that will suck everything in.

“Fortunately, they’re not,” she said. “If we replaced our sun with a black hole of the same mass, Earth wouldn’t be sucked into it. However, the lack of sunlight would be a problem.”

Shoemaker has worked in her field for about 15 years, since she was a graduate student at the University of Texas at Austin. As an astrophysicist, she considers herself to be a “detective of the universe.”

“We are using clues and evidence to determine what the universe is and how and why it looks like it does to us today,” she added.

Recently, The Whistle sat down with Shoemaker to learn more about her and her time at Tech. Here’s what we learned:

How did you get to Tech?
I was an assistant professor at The Pennsylvania State University for four years before being asked to apply to Georgia Tech. I was hired as part of an effort to initiate a research and teaching group dedicated to astrophysics, which evolved into the Center for Relativistic Astrophysics.

Tell us about your research.     
I use computational techniques to solve the equations that govern how two black holes interact with each other. The byproduct of that interaction is called “gravitational radiation.” Gravitational radiation is a kind of radiation predicted by Einstein’s theory of gravity, but it has not been directly detected (we are used to electromagnetic waves like light and microwaves).   

What is your greatest challenge associated with teaching and how do you deal with it?
When I teach large introductory classes, the challenge is to maintain a persona that is respected and approachable. My personality, which is quite friendly, is a plus and a minus for this. I think it helps me be an approachable instructor and encourages students to ask questions in class, but I also have to maintain a balance in and out of the classroom. I think the balance comes from demanding that the students respect each other and me. Little things help accomplish this such as not allowing talking in the room when one person is speaking.

What are three things that are key to making learning more engaging for students?
Humor, patience and research. I think a sense of humor is essential in teaching, second only to having the patience to let students ask questions in their own time and words. These two things help create a classroom atmosphere where a student can feel comfortable. I also try to bring up relevant, current research as often as possible so students can get a feeling for why we find physics so interesting and why it is important to society.

What piece of technology could you not live without as an instructor?
The Internet, because it allows me to research how others teach material similar to my own.

What are three things everyone should do while working at Tech?
Run the annual Pi Mile 5K, slide down that crazy water slide at the Campus Recreation Center and attend a commencement ceremony.

Where is the best place to grab lunch (on or off campus), and what do you order?
I love to order soup at La Petite Café.

Tell me something unusual about yourself.
My family and I have two Great Danes — they pretty much run the household, but they are gentle dictators.