Extrasolar Planets
Warit Mitthumsiri
Time: 12:30pm February, 22 2012
Location: Kavli, 3rd Floor Conf. Rm.

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NASA's Kepler space telescope, which aims to study the abundance of extrasolar planets, is finishing its third year in March 2012. This statistically allows planets with similar orbital periods as that of the Earth to be detected. Mankind is entering an exciting era, in which the Earth analogs such as Kepler-22b, are being discovered. I will discuss the history and current status of extrasolar planet study.

EXAFS Studies of the Thermoelectric Ba8Ga16Sn30

by Mike Kozina

12:30pm February 1, 2012, Kavli, 2nd Floor Conf. Rm.

Thermoelectric materials have the useful ability to convert a temperature gradient into an electric potential, and vice versa. This important class of materials has already found use in space and automotive technologies, but currently efficiency has become a limiting factor. It is hoped that by probing and understanding more deeply the detailed mechanisms of thermal and electrical transport in thermoelectric materials one can improve this efficiency for myriad uses in the energy sector. Here we present EXAFS data from SSRL on the thermoelectric clathrate Ba8Ga16Sn30. Extended X-ray Absorption Fine Structure (EXAFS) is an element-specific x-ray absorption technique that allows one to probe the local structure of materials up to ~6 angstroms. We show that the structure of this clathrate is particularly suited to having thermal transport properties conducive to decent thermoelectric behavior.