Fordham University            The Jesuit University of New York

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Upcoming Colloquia
Wednesday, April 23, 2014, 2:30
Freeman hall room 103

Steve Holler
Assistant Professor of Physics
Fordham University

Whispers of a photonic atom: A quest for single protein detection

The detection of trace quantities of toxic material, whether chemical or biological in nature, is vital for homeland security, quality control, and clinical diagnostics. Pathogens that reside within the body manifest within the blood and other bodily fluids. The ability to detect trace quantities of such pathogens means that treatment may be initiated earlier thereby enhancing the probability of a successful eradication of the causative agent and mitigating infection. This talk will highlight the achievements of the whispering gallery mode biosensor (WGB). In its native state, the WGB has been shown to be capable of label-free detection of single influenza virions (~100 nm); the incorporation of plasmonic enhancements has since pushed the detection limit into the realm of single protein molecules. This sensitivity has been demonstrated on thyroglobulin, a protein marker used in evaluating efficacy of thyroid cancer treatments. Based on recent experiments, we project a limit of detection of 5 kDa (~8 zg). These advances mean that label-free detection of bio-nanoparticles such as biowarfare toxins (e.g., Ricin ~32 kDa, Anthrax ~90 kDa) and disease markers (e.g., melanoma 84 kDa, breast cancer 290 kDa) are well within reach.

Wednesday, April 30 2014, 2:30
Freeman hall room 103

Michael E. Mann
Distinguished Professor of Meteorology and
Director of the Earth System Science Center
Pennsylvania State University

The Physics of Climate Change

I will review the basic underlying science of climate and climate change, including physically-based models of Earth's climate. I will motivate the use of a simple, zero-dimensional "Energy Balance Model" of Earth's radiative balance that can be used to estimate the global mean surface temperature of Earth. I will show how this model successfully reproduces the observed historical changes in global temperature, and how it can be used to assess various questions about future human-caused climate change.

Previous Colloquia

Wednesday, April 16 2014, 2:30
Freeman hall room 103

Oleg Berman
Associate Professor of Physics
NYC College of Technology

Graphene based photonics and nanophotonics

The recent results of our studies of photonics, nanophotonics and plasmonics in graphene will be presented. We analyzed the nanophotonics and nanoplasmonics in graphene nanoribbon and photonics in graphene based metamaterials. The spaser with the net amplification of surface plasmons (SPs) in doped graphene nanoribbon will be described. The plasmons in THz region can be generated in a dopped graphene nanoribbon due to pumping, nonradiative excitation by two level quantum dots located along a graphene nanoribbon. The results for the minimal population inversion per unit area, needed for the net amplification of SPs in a doped graphene nanoribbon will be reported. The dependence of the minimal population inversion on the surface plasmon wavevector, graphene nanoribbon width, doping and damping parameters necessary for the amplification of surface plasmons in the armchair grapheme nanoribbon will be described. Besides, we will present the photonic one-dimensional (1D) and two-dimensional (2D) crystals based on graphene and dielectric constituents. The frequency band structure of 1D and 2D graphene-based photonic crystal will be reported.  The possibility of tuning the graphene-based spaser and photonic crystals by the voltage gate doping will be discussed.

Wednesday, January 29, 2014, 2:30
Freeman hall room 103

Student Colloquium Series

Brigid Mulroe
Milan Paspaley-Grbavac

Drew Rotunno

Wednesday, december 4, 2013, 2:30
freeman hall room 103

Vinod Menon
CUNY: Queens College & Graduate Center
Hyperbolic Metamaterials: Towards Broadband Control of Light-Matter Interaction

The interaction of light with matter can be engineered by controlling the photonic density of states (PDOS). I will discuss our recent work on optical topological transition in strongly anisotropic metamaterials that can be used to engineer the PDOS [1]. The transition in the topology of the iso-frequency surface from a closed ellipsoid to an open hyperboloid resulting in hyperbolic dispersion manifests itself in increased rates of spontaneous emission of emitters positioned in the near-field of the metamaterial. Being a non-resonant effect, this enhancement is observed over wide spectral bandwidth. Approaches to enhance light extraction from such structures as well as anomalous cavity scaling observed in cavities fabricated using such metamaterials will be discussed. Finally, we will also discuss metal-free and tunable hyperbolic metamaterial structures.

[1] “Topological transitions in metamaterials,” H. Krishnamoorthy, Z. Jacob, E. Narimanov, I. Kretzschmar, and V. M. Menon, Science 336, 205 (2012).
Wednesday, november 13, 2013, 2:30
freeman hall room 103

Student Colloquium Series

Ariel Fragale
"Perturbative Quark Mass Renormalization for Anisotropic Lattices"

Kathryn Reddy
"Einstein's Sedimentation Equilibrium Revisited: Quantifying particle interaction through analysis of sedimentation equilibrium"

Wednesday, november 20, 2013, 2:30
freeman hall room 103

Maria Gherasimova
University of Bridgeport

Self-assembly and targeted distribution of nanoscale germanium island clusters on silicon surface

Persistent interest in the self-assembly of nanoscale semiconductor structures (quantum dots or nanowires, from several nanometers to about 100 nm in size) is partly sustained by the anticipation of reaching the fundamental limits of silicon-based device miniaturization. Precise nanoscale control of the quantum dot (QD) positioning on a substrate is desirable for many potential applications, such as the realization of quantum cellular automata (as an alternative paradigm for the logic circuits) or targeted incorporation of nanoscopic internal light sources in the photonic structures. Targeted nucleation of strained Ge islands on Si surface has been accomplished by modifying the surface with the low dose focused ion beam (FIB) patterning, enabling reliable placement of individual QDs in the closely spaced encoded locations (tens of nanometers apart) over relatively large area patterns (tens of microns in size). Ge islands are synthesized in an ultra-high vacuum environment inside a transmission electron microscope equipped with a video-rate data capture capability for in situ analysis, immediately after the FIB implantation in an adjacent chamber. Our findings indicate that the pattern assembly fidelity becomes limited by the competition between the target nucleation sites for the available Ge adatoms in the sub-100 nm site separation regime, while nearly 100 % registration rates are obtained at larger distances. To overcome this limitation, we investigate QD self-assembly on single topographical features to obtain clusters of QDs with smaller separations. Our recent work is focused on the formation of groups of Ge islands on the locations defined by the residual trenches on a footprint of a larger island that has been desorbed, as well as spontaneous cluster formation on FIB patterns.
Wednesday, october 30 2013, 2:30
freeman hall room 103

Student Colloquium Series

Katrina Colletti
"Measuring Underground Neutron Fluxes for Neutrinoless Double Beta Decay"

Joe Sweeney
"Using the Generalized Pencil-of-Function method for analyzing lattice two-point functions"

Wednesday, october 16, 2013, 2:30
freeman hall room 103

Student Colloquium Series

Jenna Kocsis
Rachel Sattler

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