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Calendar of Physics Talks Vienna
| Supported metal nanoparticle catalysts: predicting how size and support affect metal atom energetics and thus catalytic performance |
| Speaker: | Charles T. Campbell (University of Washington, Chemistry Department, USA) |
| Abstract: | Many important catalysts and electro-catalysts for energy and environmental technologies involve late transition metal nanoparticles dispersed across the surface of some support material. The activity and long-term stability of these materials depend sensitively on particle size below 5 nm, and, in this size range, upon the support material. The relationships between the energetic stability of late transition metal particles on oxide supports and their structural, electronic, chemisorption and catalytic properties have been examined in detail. We will show predictive correlations amongst the energy of the metal atoms in these nanoparticles (i.e., the metal-atom chemical potential) and their particle size as well as the nature of the support surface. The strength with which they bond adsorbates, their catalytic kinetics and their sintering rates also correlate with this metal-atom che |
| Date: | Mon, 04.09.2017 |
| Time: | 16:00 |
| Location: | TU Wien, Green Tower „A“, 5th floor, SEM.R. DA grün 05 (room no. DA05E10) |
| Contact: | Univ.Prof. Dr. Ulrike Diebold |
| Speaker: | Shahin Sheikh-Jabbari (IPM Teheran) |
| Abstract: | We show how the horizon fluff proposal works for 4d extreme Kerr. We start with constructing the `Extremal Kerr Phase Space' which are a 1-function family of solutions to 4D vacuum Einstein equations diffeomorphic to the same extremal Kerr black hole. We show the symplectic structure of this phase space remains invariant under a U(1) Kac-Moody algebra which is generated by currents J_n and Virasoro generators L_n with central charge six times angular momentum of the black hole. This symplectic symmetry algebra is well-defined everywhere on the spacetime, near the horizon or in the asymptotic flat region. Out of appropriate combination of bJ_n charges, we construct another Virasoro algebra at the same central charge. Requiring that these two Virasoro algebras should describe the same system leads us to a proposal for identifying extreme Kerr BH microstates, dubbed extreme Kerr fluff. ... |
| Date: | Tue, 05.09.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna) |
| Contact: | Daniel Grumiller |
| Yang-Baxter-models on Deformed AdSxS5 and Holographic Noncommutativity |
| Speaker: | Shahin Sheikh-Jabbari (IPM Teheran) |
| Abstract: | Yang-Baxter-model is a systematic way to generate integrable deformations of AdS5xS5. We recast the deformations as seen by open strings, where the metric is undeformed AdS5xS5 with constant string coupling, and all information about the deformation is encoded in the noncommutative (NC) parameter. We identify the deformations of AdS5 as twists of the conformal algebra, thus explaining the noncommutativity. We show that the unimodularity conditon on r-matrices for supergravity solutions translates into being divergence-free. Integrability of the -model for unimodular r-matrices implies the existence and planar integrability of the dual NC gauge theory.
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| Date: | Thu, 07.09.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna) |
| Contact: | Daniel Grumiller |
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