-
Faculty &
Research -
Undergraduate
Studies - Graduate Studies
-
Co–op
Program -
Career
Options -
News &
Announcements - Contact Us
Optical Spectroscopy of Photosynthetic Complexes
To perform photosynthesis plants, algae and bacteria possess well organized and closely coupled photosynthetic pigment-protein complexes. The information on energy transfer processes and protein dynamics contained in the narrow zero-phonon lines at low temperatures is hidden under the inhomogeneous broadening. Thus it has been proven difficult to analyze the spectroscopic properties of these complexes in sufficient detail by conventional spectroscopy methods. In this context the high resolution spectroscopy techniques as Spectral Hole Burning, Fluorescence Line Narrowing and Single molecule / Single Complex Spectroscopy are powerful tools designed to get around the inhomogeneous broadening. This study focuses mainly on the low-temperature protein dynamics of several photosynthetic protein complexes (LH2, CP43, CP29 and LHCII). The hole growth kinetics and the shape of the anti-hole due to the non-photochemical spectral hole burning have been explored and interpreted within the frame of theoretical models describing spectral diffusion due to conformational changes between nearly-identical substrates on a multi-tier protein energy landscapes.
Nicoleta Herascu
Department of Physics,
Concordia University
Explosive phase transitions in the early universe?
In moderate extensions of the Standard Model, there can be a first order phase transition associated with electroweak symmetry breaking at a temperature of order 100GeV. In this talk I will show how the physics governing the phase transition determines whether or not the transition proceeds as a detonation, with interfaces between electroweak symmetry-broken and symmetry-restored phases which propagate at almost the speed of light. Then I will summarize how this issue affects signatures of the transition, from gravitational wave backgrounds to the Creation of the matter-antimatter asymmetry at the transition.
Dr. Guy Moore
Department of Physics,
McGill University
Little Higgs Models
The LHC is now in operation, and the experiments are ready to collect data. It is believed that it will in time shed light on the mechanism of electroweak symmetry breaking, the mechanism by which most particles get their mass. In this talk I will review the problem and present an overview of various ideas of what could be verified or falsified at LHC. I will then present in more details little Higgs models.
Dr. Thomas Gregoire
Department of Physics,
Carleton University
Testing String Theory with Cosmological Observations
The inflationary scenario is the current paradigm of early universe cosmology. The scenario, however, suffers from some key conceptual problems. In light of these problems, it is important to consider the possibility of other scenarios. I will present an early universe scenario based on some fundamental principles of superstring theory. This scenario may lead to a non-singular cosmology. It gives rise to a mechanism of structure formation different from the one which is operative in inflationary cosmology. The scenario is consistent with current observations but makes predictions concerning the spectrum of gravitational waves with which it can be differentiated from inflationary cosmology.
Dr. Robert Brandenberger
Department of Physics,
McGill University
Spin Transport via V-Cp-Fe-Cp Multidecker Sandwich Molecules
Electronic spin transport through (CpFeCpV)_n multidecker wire sandwiched between magnetic Nickel (Ni) electrodes is simulated in the linear response regime based on density functional theory. The effects of the molecule-electrode contact and molecule wire length on its spin filter behavior have been studied. The amplitude and the sign of the spin filter efficiency can be manipulated by choosing the contact condition (e.g. anchoring groups, absorbing positions on Ni electrodes surface). The performance of the spin filter can be further manipulated by adjusting the length of the molecule wire. Various ways to realize nearly perfect spin-filters are illustrated.
Dr. Xuefeng Wang
Department of Physics,
Soochow University, Suzhou, China
Combination of Organic Semiconductors and Nanomaterials for Device Fabrication
The combination of organic semiconductors and nanomaterials offers the possibility of development of easy processing and low cost devices for various applications. Here we will present the fabrication of two such devices: The first device is a bi-stable memory devices made by embedding gold nanoparticles in an organic semiconductor. We will also present the fabrication of transparent carbon nanotubes electrodes that could be used on organic light emitting diodes (OLEDs) or organic solar cells.
Dr. Ricardo Izquierdo
Professor of Microelectronic Engineering,
Computer Science Department, UQAM
Algorithmic Cooling: Putting a New Spin on the Identification of Molecules
In this talk I will present Algorithmic Cooling of Spins, which is potentially the first near-future application of quantum computing devices. I will explain how straightforward quantum algorithms combined with novel entropy manipulations can result in a method to improve the identification of molecules.
Dr. Tal Mor
Computer Science Department,
Technion University & Visiting Professor, Université de Montréal
Left-Right Symmetric Model and W_R Gauge Boson Signatures at the LHC
With the advent of the LHC, it is important to devise clear test for Physics Beyond the Standard Model. Such physics could manifest itself in the form of new charged bosons, whose presence is most naturally occurring in left-right symmetric models (LRSM). We present a version of the Model in which W_R gauge bosons are preferentially produced at LHC and analyze their decay properties. We include constraints from low energy phenomenology. With all the restrictions, and including the background, we find that we can still obtain measurable signals for the new charged bosons.
Alper Hayreter
Department of Physics, Concordia University
Direction-Dependent Tunneling and Wave-Vector Filtering In Graphene Nanostructures
We study tunneling through various graphene microstructures. The transmission through barriers depends strongly on the angle of incidence φ and for φ=0 shows the well-known Klein effect. We also study resonant electronic transmission through graphene-based double barriers (wells) as a function of the incident wave vector, the widths and heights (depths) of the barriers (wells), and the separation between them. Resonant features in the transmission result from resonant electron states in the wells or hole states in the barriers and strongly influence the ballistic conductance of the structures.
Further, we show that the angular range of the transmission through magnetic barrier structures can be efficiently controlled in single-layer and bi-layer graphene and this renders the structures efficient wave vector filters. As the number of magnetic barriers increases this range shrinks, the gaps in the transmission versus energy become wider, and the conductance oscillates with the Fermi energy.
Dr. P. Vasilopoulos,
Department of Physics, Concordia University
Page Title: News & Announcements - Concordia University - Montreal, Quebec, Canada
Page URL:http://bohr.concordia.ca/newsandannouncements/index.php ...index.php
Date Printed: Sun March 21, 2010