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Physics Colloquium - Friday, Oct. 10th, 2008, 4:00 P.M.

E300 Math/Science Center; Refreshments at 3:30 P.M. in Room E200

David Waldeck - Chemistry Department, University of Pittsburgh

Fundamental Studies of Electron Tunneling and Transport between Biomolecules and Electrodes

I will discuss our recent work investigating the nature of electron transfer between a metal electrode and biomolecules, both proteins and oligonucleotides. By using well-defined monomolecular films on metal surfaces and manipulating the properties of the films we are able to manipulate and control features of the electron transfer rate. In particular, I will describe electrochemical studies of the electron transfer between cytochrome c and Au electrodes in which we are able to modify the dominant electron tunneling pathway by changing the chemical bonding of the protein to the electrode. Our studies also reveal a change in the electron transfer mechanism that is linked to the 'adiabaticity' of the electron transfer rate. In addition to these protein studies, I will discuss electron transport through peptide nucleic acid and how it depends on the nature of the nucleobases and the length of the oligonucleotide. By changing the length of the oligonucleotides we are able to observe the transition between electron tunneling and charge hopping through such films. In each case we draw comparisons between the observations and the predictions of simple theoretical models.