Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session P4: Celebrating 50 Years of Lasers in Condensed Matter Physics: Dynamics & Imaging |
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Sponsoring Units: DPOLY Chair: Marcus Cicerone, National Institute of Standards and Technology Room: Oregon Ballroom 204 |
Wednesday, March 17, 2010 8:00AM - 8:36AM |
P4.00001: Transport dynamics -- one particle at a time Invited Speaker: By watching particles and molecules diffuse, one-by-one, the full displacement probability distribution can be measured, enabling one to see experimentally how, how fast, and with what fidelity to classical assumptions, particles and molecules diffuse through complex environments. This allows us to measuring the confining tube potential through which thin actin filaments reptate, and also some of the amazing differences in diffusion rate between colloidal particles and phospholipid vesicles of the same size. Pervasively, we find that Brownian diffusion can be non-Gaussian. [Preview Abstract] |
Wednesday, March 17, 2010 8:36AM - 9:12AM |
P4.00002: Mid-infrared pulse shaping permits the pathway of amyloid aggregation to be determined with rapid-scan 2D IR spectroscopy Invited Speaker: We have developed a means for rapidly acquiring 2D IR spectra in a continuous fashion to monitoring protein kinetics. Our method relies on a mid-IR pulse shaper that generates precise pulse trains for collecting 2D IR spectra. The phase, amplitude and now the polarization of the pulse trains can be automatically generated without optical alignment, which produces higher accuracy spectra in a much easier fashion than with standard 4-wave mixing. Using this new technology as well as site-specific isotope labeling, we have measured the development of secondary structures for six residues during the aggregation process of the 37-residue polypeptide associated with type 2 diabetes, the human islet amyloid polypeptide (hIAPP), also called amylin. By monitoring the kinetics at six different labeled sites, we find that the peptides initially develop well ordered structures near the ordered loop of the fibrils, followed by formation of the two parallel $\beta$-sheets with the N-terminal $\beta $-sheet likely forming before the C-terminal sheet. This experimental approach provides residue-by-residue details on the aggregation pathway of hIAPP fibril formation as well as a general methodology for studying other amyloid forming proteins without the use of structure perturbing labels. Moreover, this approach is also applicable to membrane catalyzed amyloid formation, and experiments along these lines will be presented as well. [Preview Abstract] |
Wednesday, March 17, 2010 9:12AM - 9:48AM |
P4.00003: Entangled Photon Spectroscopy with Organic Materials Invited Speaker: The use of entangled light for the purposes of spectroscopy as well as for applications in sensing, quantum microscopy, and quantum lithography will be discussed. The Entangled Two Photon Absorption (ETPA) cross-section of a set of nonlinear optical materials, with known, and large, classical two-photon absorption (TPA) cross-sections, but of differing geometry, donor-acceptor strength, and charge-transfer character, will be presented in this talk. Materials with classical TPA cross-sections attributed to virtual transitions involving an intermediate state are found to have measurable, and large, ETPA cross-sections. However, it is also found that the materials whose (large) classical TPA cross-section is attributed to a dipole transition, without involvement of an intermediate state, are nearly transparent to entangled photons. From these results, it will be shown that entangled photons are highly sensitive to the intermediate states of a nonlinear optical organic molecules and macromolecular materials. These results have great impact in the development of materials for entangled photon sensing applications. [Preview Abstract] |
Wednesday, March 17, 2010 9:48AM - 10:24AM |
P4.00004: Single Molecule Studies of Conjugated Polymers Invited Speaker: |
Wednesday, March 17, 2010 10:24AM - 11:00AM |
P4.00005: Light Scattering Studies of Dynamics of Soft Materials Invited Speaker: Dynamics is the key to many unique properties of Soft Materials. However, its understanding remains a great challenge. In this talk, we overview applications of light scattering techniques (Raman, Brillouin and Photon-correlation spectroscopy) to studies of dynamics of glass forming systems and glass transition phenomenon, polymers and biological macromolecules. General picture of dynamics of soft materials on different time and length scales is presented. The role of light scattering studies in development of this general picture is emphasized. [Preview Abstract] |
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