The Department of Physics & Astronomy has received $103,000 in campus Capital Facilities & Remodeling funds to renovate the 4th floor astronomy lab in the South Physics building. The new facility will house education and public outreach activities for the South Physics Observatory, handle analysis of the data from the Sloan Digital Sky Survey III, and serve as the control room for the Willard. L. Eccles Observatory at Frisco Peak, Utah.
Congratulations to Dr. Shanti Deemyad, whose proposal, "Establishing Collaboration with NASA AMES Labs via EPSCoR Science Program", was recently selected for a travel grant from NASA EPSCoR RID program.
Together with her students, Anne Marie Schaeffer and William Talmadge (pictured at left) will be visiting the NASA Ames laboratory to establish collaborations this coming October.
From the Clark Planetarium's website.
Dr. John Belz
June 21, 2012
Clark Planetarium
Beginning in June, join the Clark Planetarium for their new open format lecture series, Night School. Topics range across a wide spectrum of scientific disciplines and the open format encourages group discussion and exploration.
Dr. John Belz, will launch the Night School series on Thursday, June 21st from 7pm – 8pm, with his talk, “Two Through Your Head Every Second – Cosmic Rays”. High energy cosmic rays are important to our understanding of the universe, and John Belz uncovers what cosmic rays are, their origin, and how they are detected.
Night School sessions are hosted in the Hansen Dome Theater, and are followed by light refreshments in the Third Floor Exhibits area. Admission is $2. Members are free.
More information available here.
Thesis Defense
William J. Baker
Monday, June 11, 2012
10:00am (110 INSCC)
Title: Properties & Applications of Coherently Controlled Spin-Dependent Charge Carrier Transitions in MEH-PPV
Abstract:
This thesis is focused on the investigation of the fundamental physical nature and potential technical applications of spin-dependent charge carrier recombination in poly[2-methoxy-5-(20-ethyl-hexyloxy)-1,4-phenylene vinylene (MEH-PPV), a π-conjugated polymer which has been utilized as organic thin film semiconductor. Pulsed electrically detected magnetic resonance (pEDMR) spectroscopy was used to observe how coherent spin motion of paramagnetic charge carrier states (so called polarons) control the macroscopic conductivity of thin (~100nm) MEH-PPV layers under different charge carrier injection regimes. The pEDMR experiments were conducted at frequencies covering almost three orders of magnitude (~20MHz to ~10GHz) and at temperatures between ~5K and ~300k. The measurements revealed that under balanced bipolar injection, the conductivity of MEH-PPV is influenced at any temperature by the polaron pair (PP) mechanism, a spin-dependent process previously described in the literature. The experiments showed that PPs are weakly exchange- and dipolar-coupled pairs but they are strongly influenced by proton induced hyperfine fields. Electrical detection of coherent polaron-spin motion revealed extraordinary long coherence times (order of μs) at room temperature which could qualify PPs for quantum information applications. The PP mechanism was also demonstrated to work as an extraordinary sensitive, 50 nT Hz-1/2, organic thin film probe which uses the polarons gyromagnetic ratio λ as magnetic field standard. λ was observed to be independent of temperature, device-current, and -bias, and degradation of the MEH-PPV device. In addition to the PP mechanism, another spin-dependent process previously described in the literature was confirmed to significantly influence conductivity in MEH-PPV: Triplet exciton -polaron recombination.
