לוח שנה משולב

Despite decades of theoretical and observational work, the progenitor
systems of Type ia Supernovae have never been identified. I will
describe the leading theoretical scenarios for Type Ia progenitors and
discuss their strengths and weaknesses. I will also present results
from the SWARMS survey, an ongoing effort to identify SN Ia
progenitors by mining the spectroscopic data base of white dwarfs in
the Sloan Digital Sky Survey.

The idea of using an individual molecule as an electronic active element at the nano-scale is attractive because of the rich structural possibilities offered by chemical synthesis as well as the unique mechanical and electronic properties of molecules. In order to control and modify the electronic conductance of electrode-molecule-electrode junctions, the fundamental aspects of electronic transport through molecules should be explored. We study the relation between structure, dynamics and conductance of a single molecule trapped between two metallic electrodes. Here I will focus on the following subjects:
1) The effect of molecular vibrations on the conductance of a single-molecule junction.
A molecule bridging between two electrodes is a unique electro-mechanical nanosystem since it combines mechanical motion (molecular vibrations) and electron transport at the atomic scale. The effect of molecular vibrations on the conductance of a single-molecule has been recently much debated in theory. We have found a clear crossover between conductance suppression and enhancement by molecular vibrations, where the measurement of shot noise provides the missing link between our observations and the theoretical models.
2) A highly conductive single-molecule junction.
The common approach for anchoring a molecule to electrodes utilizes reactive side groups that bond the molecule to metallic electrodes. This leads to a limited and not well-defined conductivity since the side groups act as potential barriers and they are prone to structural changes. Here we demonstrate a new approach where direct bonding of a pi-conjugated molecule (benzene) to metallic (Pt) electrodes can lead to a stable and highly conductive molecular junction. In addition, our findings combined with calculations suggest that stretching the junction can tune the conductivity by tilting the molecule.