Dresden 2006 – wissenschaftliches Programm

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SYIM: Intrinsic Modes

SYIM 1: Intrinsic Modes I

SYIM 1.1: Hauptvortrag

Donnerstag, 30. März 2006, 14:30–15:00, HSZ 04

Energy Transport and Vibrational Self-Trapping in Peptide Models and Peptide Helices — •Peter Hamm — Physikalisch-Chemisches Institut, Universität Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland

Based on femtosecond IR-pump-probe spectroscopy, we have recently provided compelling experimental evidence that vibrationally self-trapped states in the amide I band of hydrogen-bonded model peptides and peptide models does indeed exist [1-3]. We have furthermore shown that polaron theory can explain the anomalous temperature dependence of the amide I spectrum of crystalline ACN only if taking into account the 3D nature of the system [4]. I will briefly review this work.
As an alternative approach to study energy flow in peptide helices, we have constructed a rigid helix with a dye molecule (azobenzene) attached to one side. The dye is electronically excited and dissipates the energy on an ultrafast 200 fs timescale through internal conversion, thereby locally heating the helix on one side. Vibrational labels attached at various distances from the dye molecule act as local thermometers and directly report on the energy flow through the helix. We hope to be able to distinguish diffusive from ballistic energy transport. I will report on the results of ongoing experiments.
[1] J. Edler, P.Hamm, A. C. Scott, Phys. Rev. Lett. 88 (2002) 067403
[2] J. Edler, P. Hamm, J. Chem. Phys. 117 (2002) 2415.
[3] J. Edler, R. Pfister, V. Pouthier, C. Falvo and P. Hamm, Phys. Rev. Lett. 93, (2004) 106405
[4] P. Hamm, J. Edler, Phys. Rev. B, submitted