Events at Physics
Events on Friday, February 1st, 2019
- R. G. Herb Condensed Matter Seminar
- Competing orders in non-centrosymmetric superconductors
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Maxim Khodas
- Abstract: As a motivation I review several recent experiments on transition metal dichalcogenides. Then I will present what is known about these materials and what makes there response to the magnetic field special. I will then review the spin-orbit coupling based on symmetry considerations. Then I'll focus on the singlet to triplet conversion induced by the Zeeman field. Finally I'd discuss the effect this has on the critical field.
- Host: Levchenko
- Department Meeting
- Time: 11:30 am
- Place: B343 STERLING HALL
- Speaker: Sridhara Dasu, UW-Madison
- Host: Sridhara Dasu
- Astronomy Colloquium
- UPDATED TIME AND DATE
- Infrared Spectroscopy of Stars and Planets
- Time: 2:30 pm
- Place: 4421 Sterling Hall, Coffee and cookies 2:30 PM, Talk begins 2:45 PM
- Speaker: Ian Crossfield, MIT Dept of Physics
- Abstract: Extrasolar planets and cool stars emit most of their light beyond the range of standard optical observations. These objects are often best studied using infrared spectroscopy. I will present recent results from my group on two topics: space-based IR spectroscopy of exoplanet atmospheres, and ground-based, high-resolution spectroscopy of both planets and stars. I will also conclude with a brief discussing of how future IR-optimized observatories will also enable exciting new science in these areas.
- Host: Amy Barger
- Physics Department Colloquium
- Making Movies of Molecules - The Application of X-ray Lasers
- Time: 3:30 pm
- Place: 2241 chamberlin Hall
- Speaker: Junko Yano, LBNL
- Abstract: Our group is studying the mechanisms of the catalytic reactions in both natural and inorganic systems. Using various X-ray techniques as tools, we are studying how the catalysts do multielectron reactions, by following the reaction under functional conditions.
We have developed spectroscopy and diffraction techniques necessary to fully utilize the capability of the X-ray Free Electron Laser facilities (XFELs) for a wide variety of metalloenzymes, and to study their chemistry under functional conditions. One of such methods is simultaneous data collection for X-ray crystallography and X-ray spectroscopy, to look at the overall structural changes of proteins and the chemical changes at metal catalytic sites. In parallel to the detection techniques, we have developed an efficient sample delivery method that involves deposition of droplets on a conveyor belt. This 'Droplet on Tape' (DOT) method, delivers a single drop of the crystal suspension or solution sample onto a tape, which then can be transported to the X ray intersection point with a variable delay in time. In the process, the sample is photochemically or chemically activated at various time delays to capture reaction intermediates with crystallography and spectroscopy.
The presentation will cover our group's recent results of metalloenzyme research, in particular, for the study of the water oxidation reaction in natural photosynthesis, using X-ray crystallography and X-ray spectroscopy at LCLS (LINAC Coherent Light Source).
Kern, J. et al. Simultaneous femtosecond X-ray spectroscopy and diffraction of Fuller, F. D. et al. Drop-on-demand sample delivery for studying biocatalysts in action at XFELs Nat. Methods 14, 443 (2017).
Kubin, M. et al. Soft x-ray absorption spectroscopy of metalloproteins and high-valent metal-complexes at room temperature using free-electron lasers, Struct. Dynamics 4, 054307 (2017)
Kern, J. et al. Structures of the intermediates of Kok’s photosynthetic water oxidation clock. Nature 563, 421 (2018).
- Host: Pupa Gilbert