Spring 2014 Seminars
January 20, 2014
Martin Luther King Jr. Day
January 27, 2014
A Tale of Two Colloids: Order and Disorder on a Soft Substrate.
Andrew B. Croll
February 3, 2014
Molecular Simulation of Physical Aging in Ultrathin Polymer Films
February 10, 2014
Multiple Exciton Generation in Nanometer-sized Silicon Nanoparticles
February 17, 2014
February 24, 2014
Bekele, Damith, others!
March 3, 2014
APS March Meeting
March 10, 2014
March 17, 2014
March 24, 2014
Determination of pK Values of Ionizable Residues in Pentapeptides and in SNase protein.
Guilherme Volpe Bossa
March 31, 2014
April 7, 2014
Following molecules out of equilibrium: From the formation of nanoparticles to the complex behavior of strongly driven systems.
April 14, 2014
Coherent Raman Standoff Detection with Shaped Femtosecond Pulses
April 21, 2014
April 28, 2014
Answer First: Applying the heuristic-analytic theory of reasoning to examine student intuitive thinking in the context of physics
May 5, 2014
Hyperspectral Imaging: Optical System Design Considerations for an orbiting imaging Fourier Transform Spectrometer
May 12, 2014
Excitons in Nanoscale Semiconductor Structures from the Bethe-Salpeter Equation
May 19, 2014
Bacterial Adhesion on Material Surfaces
Excitions in Nanoscale Semiconductor Structures from the Bethe-Salpeter Equation.
Department of Physics, North Dakota State University
Monday, May 12, 2014, 3:00-4:00pm
221 South Engineering
Deyan is a graduate student working with Andrei Kryjevski
Excitons are bound states of electrons and holes held together by Coulomb attraction. In semiconductor nanoparticles of size comparable to or smaller than the Exciton-Bohr radius excitons have significant effect on the density of states of the system. The standard way of calculating energies and wave functions of excitons is to solve the Bethe Salpeter equation (BSE) in the basis of Kohn-Sham (KS) orbitals and energies, the output of Density Functional Theory. In this work, we derive BSE using basic tools of many body quantum mechanics. Namely, we compute the matrix of the full, interacting Hamiltonian in the basis of electron-hole KS states, and, in particular, derive direct and exchange Coulomb terms present in the standard BSE. The method is then applied to calculating energies and wave functions of low energy excitons in a nm-sized Hydrogenated crystalline Silicon quantum dot.
Bacterial Adhesion on Material Surfaces.
Dr. Klemen Bohinc
Faculty of Health Sciences, University of Ljublijana, Slovenia
Monday, May 19, 2014, 3:30-4:30pm (Refreshments will be served at 3:00).
221 South Engineering
Bacterial adhesion can be controlled by different material surface characteristics like surface roughness, on which we concentrate in our study. Different glass surfaces were prepared by polishing the glass plates with different gradations. The corresponding surface roughness was controlled by atomic force microscope and profilometer. The rate of adhered bacteria on glass surfaces was determined with spectrophotometer and scanning electron microscopy. Our results showed that the rate of adhered bacteria increases with increasing surface roughness. The increased adhesion of bacteria on more rough surfaces is the interplay between the increasing effective surface and increasing number of defects on the surface.