Events at Physics
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Events on Thursday, November 2nd, 2017
- Wisconsin Science Festival
- IceCube at Wisconsin Science Festival
- Time: 9:00 am
- Place: Discovery Building
- Speaker: IceCube faculty and staff
- Abstract: Come learn more about IceCube at the Wisconsin Science Festival. We will be at the Discovery Building from Nov 2nd and Nov 3rd, 9am-2pm and Nov 4th from 10am-3pm! We will have interactive activities for kids and adults, including our IceCube LED display.
- R. G. Herb Condensed Matter Seminar
- Design and Synthesis of 1D and 2D Nanomaterials Away from Equilibrium
- Time: 10:00 am
- Place: Chamberlin 5310
- Speaker: Xudong Wang, UW-Madison (Materials Science and Engineering)
- Abstract: Morphology is one essential element that gives rise to extraordinary physical, chemical, and mechanical properties in nanomaterials. Precise morphology control of nanomaterials is a notorious task, which heavily relies on fundamental understanding of the governing mechanisms and kinetics at the nanoscale. In this talk, I will present our three recent discoveries of the growth kinetics in 1D and 2D nanomaterial evolution. Firstly, the surface-reaction-limited pulsed chemical vapor deposition (SPCVD) technique will be discussed. The SPCVD technique effectively decouples the crystal growth from precursor vapor concentration, thus makes the conform growth of dense NW arrays inside highly-confined submicron-sized spaces possible. The evolution of NRs was found to be a manifestation of the Ostwald-Lussac Law. SPCVD opens a new route toward the design and creation of complex 3D hierarchical nanostructures, which can advantageously impact the devices performance of solar energy harvesting. Secondly, I will present our discovery of the wedding cake growth mechanism in the formation of 1D and 2D ZnO nanostructures. Within a narrow kinetic window, the surfaces of the 1D and 2D structures were covered with a unique concentric terrace feature, different from the screw-dislocation features. An interesting 1D to 2D morphology transition was found during the wedding cake growth, when the adatoms overcome the Ehrlich-Schwoebel (ES) barrier. At last, I will present a new ionic layer epitaxy (ILE) technique that uses surfactant monolayers to serve as soft templates guiding the nucleation and growth of 2D nanomaterials in large area beyond the limitation of van der Waals solids. One- to two-nm-thick, single-crystalline free-standing ZnO nanosheets with sizes up to tens of micrometers were synthesized at the water-air interface. ILE of other metals and oxides have also been proved to be successful.
- Host: Alex Levchenko
- Atomic Physics Seminar
- "The magnetic interstellar medium: cosmological and astrophysical perspectives"
- Time: 3:30 pm
- Place: 4421 Sterling Hall, Coffee and cookies 3:30 pm, Talk begins at 3:45 pm
- Speaker: Susan Clark, Institute for Advanced Study
- Abstract: The interstellar medium (ISM) is multi-phase, turbulent, and magnetic. This makes the ISM an ideal laboratory for studying the multi-scale physics of star formation and galactic evolution. This unfortunately also makes the ISM a formidable foreground for cosmology experiments, such as the search for inflationary gravitational wave B-mode polarization in the cosmic microwave background. I will discuss recent work on magnetic fields in the diffuse ISM, with a particular focus on insights from high-dynamic range observations of neutral hydrogen and polarized dust emission. Novel tools for quantifying the morphology of interstellar material are enabling new probes of the ambient magnetic field structure, and thus a better characterization of polarized cosmological foregrounds. The hunt for primordial signals is now inextricably linked to our understanding of the magnetic ISM.
- Host: Prof Alexander Lazarian