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Date | Host | Speaker | Title of the talk | Abstract |
Aug. 30 | Hor | Dr. Xinhua Liang Chemical & Biological Engineering, Missouri S&T |
Ultrathin Films Coated on
Ultrafine Particles via Atomic/Molecular Layer Deposition (ALD/MLD) |
Fine
particles have gained increased interest in a variety of fields for different
applications. The performance of the particle applications could be improved
when such particles are coated with ultra-thin inorganic or organic films.
Atomic layer deposition (ALD) and molecular layer deposition (MLD) are thin
film growth techniques based on sequential, self-limiting surface chemical
reactions, and have been employed to grow films with precise atomic or
molecular layer control. ALD has focused principally on the formation of thin
film oxides, metals, or semiconductor alloys on solid substrates. MLD, which is
similar to ALD, can be utilized to deposit polymer films. The MLD technique
offers the same advantages for polymer film deposition as ALD does for ceramic
films. MLD can also deposit hybrid polymer films using suitable precursors.
Fluidized bed reactors are well suited for large scale coating operations. In
this process, the particles are normally fluidized under reduced pressure
conditions using an inert gas. Precursor doses can be delivered to the bed of
particles sequentially and, in most cases, can be utilized at nearly 100%
efficiency without precursor breakthrough and loss with the assistance of an
in-line downstream mass spectrometer. Several examples of the applications of
conformal ALD and MLD coatings will be discussed, including ultra-thin
microporous/mesoporous metal oxide films prepared from dense hybrid MLD polymer
films, well-dispersed thermally stable noble metal nanoparticles prepared by
ALD, and biocompatible interface films deposited within porous polymers by ALD
for tissue engineering application. |
Sept. 6 | Medvedeva |
Dr. Mohsen
Asle Zaeem Materials Science and Engineering, Missouri S&T |
Phase Field–Finite Element Models for Microstructural Evolution |
Predicting and controlling nano- and
microstructural evolution of materials play important roles in design and
manufacturing of engineering structures. With recent progress in computer
resources, computational models have become commanding modules in materials science
and engineering. Recently, phase field modeling has emerged as a powerful
computational tool to study nano- and microstructural evolution, and
consequently to predict material properties and mechanical behavior of alloys
during different engineering processes. A broad spectrum of moving boundary
problems in engineering and physics, such as those in solidification, grain
growth, multi-phase fluid flow, and solid state phase transformation, can be
successfully simulated with phase field models. |
Sept. 13 | Hagen | Dr. Andrew Detwiler |
Current Problems in Thunderstorm
Electrification and New Observing Systems for Thunderstorm Studies |
Progress is being made in in studies of thunderstorm
electrification. Lightning mapping array (LMA) systems provide observations of
all lightning in storms, both cloud-to-ground and intercloud. Locations in
storms where initial lightning breakdown occurs can be identified. The
distribution of polarity of charge in thunderstorms also can be discerned from
analysis of LMA data. In situ measurements using airborne platforms are
providing more detailed mapping of charge regions and in addition provide
microphysical observations to test theories of charge separation.
The detailed physics of the charge separation discharge process and
the lightning discharge process remains an active area of research,
particularly the physics behind separation of charge during non-inductive
ice particle collisions, the physics of triggering the initial
breakdown in a lightning flash, the emission of X-ray and gamma radiation
during some lightning events, and the variable charge
distribution in different thunderstorms. New instrumentation and research
platforms will facilitate advances in these areas. |
Sept. 20 | ||||
Sept. 27 | Hor | Dr. Edward Kinzel Mechanicall & Aerospace Engineering, Missouri S&T |
Optical Antennas for Nanolithography, Near-field Imaging, and Energy Applications |
Antennas are
structures that couple far-field propagating waves to a localized near-field
source. Most people have some
familiarity with antennas at radio/microwave frequencies, but the same concepts
can be scaled down to the infrared/optical wavelengths. This permits light to be concentrated below
the diffraction limit which is useful for multiple applications such as
nanofabrication, imaging/spectroscopy, and data storage. Antenna elements also form the building
blocks of metamaterials. These are materials that can be engineered to have
properties not found in nature. By careful design of the antenna structure, a
surface can be engineered with specific absorbance/reflectance/transmittance at
a given wavelength/angle of incidence. This involves scaling down Frequency
Selective Surfaces (FSS) concepts. In
the last decade, this approach has been used to create devices such as Fresnel
zone plates, band pass/stop filters, and quarter waveplates at infrared
frequencies. From Kirchhoff’s law and
reciprocity the emissivity of a surface is equal to its absorptivity. The ability to design, fabricate, and
characterize these structures opens up new possibilities for radiative
heat-transfer and energy harvesting. In this talk I
will present the design of ridge aperture-based antennas and their
implementation for direct-write nanolithography. This system has been successfully
demonstrated writing multiple sub-100 nm lines in parallel. This work also led
to studying arrays of apertures at infrared frequencies for polarization, spectral
control, as well as light-trapping in weakly absorbing media such as solar
cells. I will then describe the
development of a scanning near-field optical microscope for resolving the
amplitude and phase responses of antennas and FSSs in the infrared. Finally I will present my recent studies of structures
showing control of both the reflected phase as well unity absorptivity/emissivity
over a spectral region. |
Oct. 5 (Friday 4.00 pm) |
Bieniek | Dr. John Farley University of Nevada, Las Vegas |
Going beyond the lecture: What have we learned from physics education research? |
In recent decades, physics research has been dramatically transformed by the use of computers, lasers, and automated instruments. In contrast, physics education has changed very little. Traditional lectures reign supreme. The new discipline of physics education research has applied the scientific method to the process of teaching and learning. A critical advance is the use of pre- and post-testing of classes to measure student learning. One surprising conclusion is that traditional lecturing is remarkably ineffective. I discuss a number of ways in which teaching can be improved, using pedagogy that is more effective than traditional lecturing. Finally, I discuss the NSF-funded physics Research Experience for Undergraduates (REU) program at UNLV, one of the longest-running REU programs in the country, which teaches undergraduates how to conduct physics research. |
Oct. 12 (Friday 4.00 pm) |
Schulz | Dr. Jason Alexander Cold Atom Optics Group Sensors and Electron Devices Directorate U.S.Army Research Laboratory |
Experiments
in Cold Atom Optics at the U.S. Army Research Laboratory |
I will describe the work we have been doing in the Cold Atom Optics Group at U.S. Army Research Laboratory. After a brief review of the basics of laser cooling and trapping I will discuss our progress towards a couple of experiments on manipulating cold atoms on a chip for quantum sensing. The first experiments are directed towards developing a compact atom interferometer on an atom chip using a double-well potential. The interferometer uses 87Rb atoms magnetically confined in an atomic waveguide produced by wires on the surface of a lithographically patterned chip. Finite element modeling of combinations of different current configurations with various external bias fields indicated a means of coherently splitting the atomic cloud through dynamically adjusting the currents and bias fields. In these experiments we investigate real-time transformations between different double-well configurations adiabatically and non-adiabatically, and study their effects on the initially trapped atoms. Coherence properties of the two atomic wavepackets are examined. In another set of experiments we investigate the properties of bosons confined to (quasi) one dimension in our magnetic waveguide. When the atom-atom repulsive interaction becomes much larger than the kinetic energy, bosons confined in one dimension can enter a new state of matter, the Tonks-Girardeau gas, in which they behave like non-interacting fermions. However, the bosons can still occupy the same momentum state and therefore the gas cannot be fully described by either Bose-Einstein or Fermi-Dirac statistics. This transition has been observed in optical lattices but not in magnetic atom chip waveguides. We discuss the conditions for obtaining a Tonks-Girardeau gas with 87Rb atoms in our atom chip waveguide as well as a novel signature for observing the transition in our system. Finally, I would like to spend a few minutes proposing some new experiments. These experiments would combine the techniques of laser cooling and atom chip traps with the cold target recoil ion momentum spectroscopy (COLTRIMS) techniques I learned at MS&T from Professor Schulz to investigate few-body dynamics in cold and ultracold collisions, In these collisions, mostly total cross-sections are measured assuming a certain model (the 1st Born approximation) and determined by atom trap loss rates. |
Oct. 18 | Schulz | Dr. Nhan V. Tran Fermilab |
Discovery of the Higgs boson or something
like it |
On July 4th, 2012, the CMS and ATLAS collaborations at
the Large Hadron Collider announced the discovery of a new bosonic particle at
a mass near 125 GeV. It is one of the most significant results in high
energy particle physics over the past 30 years. I will give an overview
of the search at CMS for the Higgs boson hypothesized by the Standard Model of
particle physics, including a broad introduction to general experimental
techniques, and a review of the anatomy of the discovery. There will also
be a brief discussion on the implications of the discovery on physics beyond
the Standard Model and what next steps are planned to better characterize this
new particle. |
Oct. 25 | ||||
Nov. 1 | Jentschura | Dr. Robert Ehrlich George Mason University |
The Superluminal Neutrino Hypothesis: Searching for Tachyons or Unicorns? |
With
a recent claim of superluminal neutrinos shown to be in error, 2012 may not be
a propitious time to review the evidence that one or more neutrinos may indeed
be tachyons with v > c and m^2 < 0. Nevertheless, there are a
growing number of observations that continue to suggest this possibility --
albeit with a mass-squared having a much smaller magnitude than was implied by
the original OPERA claim. In addition to summarizing this evidence, this
talk also discusses a possible 3 + 3 mirror neutrino model incorporating one
superluminal neutrino pair, as well as a large number and variety of tests of
the superluminal neutrino hypothesis. One of these tests involves a
surprising prediction concerning an unreported aspect of the SN 1987A neutrino
data. |
Nov. 8 | Hor | Dr. Michael Schulz Missouri S&T |
The Overlooked Role of Projectile Coherence in Atomic Fragmentation Processes |
It is
well established that the Schrödinger equation is not analytically solvable for
more than two mutually interacting particles even if the underlying force is
precisely known. This fundamental problem, known as the few-body problem,
has motivated atomic scattering research for decades and resisted a general
solution until today. However, for certain kinematic regimes the few-body
dynamics in some atomic fragmentation processes were thought to be basically
understood until about a decade ago. This assumption was seriously shaken
when qualitative and puzzling discrepancies between experiment and theory were
found for a situation that was regarded as relatively “easy” for theory.
These studies were vividly debated for many years, but a major breakthrough towards
a solution was only achieved recently by experimental developments. It
was demonstrated that atomic scattering cross sections can depend on the
projectile coherence properties and, since this was not accounted for in
theory, that this could explain some of the discrepancies between theory and
experiment in past studies. In this talk a series of experimental studies
on the role of projectile coherence will be presented and analyzed. |
Nov. 15 | Hor |
Dr. Thomas Vojta Missouri S&T |
The 2012 Nobel Prize in Physics | |
Nov. 29 | Hor | 19th Annual Laird D. Schearer Prize Competition |