Physics of bio-assembled nanostructures: chirality, Fano effect and hot plasmonic electrons

Date

Aug 24, 2015

Time

4:30 PM - 5:30 PM

Speaker

Alexander Govorov

Affiliation

Ohio University

Series

MPI-PKS Kolloquium

Language

en

Main Topic

Physik

Other Topics

Physik

Host

nanosa15 Workshop

Description

The talk will describe optical and electronic properties of nanostructures assembled from interacting plasmonic, excitonic and bimolecular elements. The combination of crystalline nanocrystals having superior optical responses (which are much stronger than the molecular ones) and bio-molecular building blocks (DNAs, proteins, polymers) is a very intriguing opportunity. New physical effects in these nanostructures may come from Coulomb, electromagnetic and tunnel interactions. The talk will include a few examples: (1) When constructing our structures we were certainly inspired by nature. Helical plasmonic nanostructures, made from gold nanoparticles and DNA-origami, have the geometry of α-helix protein. Such plasmonic bio-assemblies exhibit an unprecedented strength of optical activity (circular dichroism) in the visible wavelength interval [1,2]. (2) Nano-assemblies from semiconductor nanocrystals demonstrate ultra-fast Förster energy transfer [3] and resemble natural photosynthetic systems. (3) Metal nanocrystals exhibit strong collective resonances, so-called plasmon excitations. The wave functions of plasmons are complex and we treat such wave functions using the Kinetic DFT recently developed by us [4]. In the next step, we apply the Kinetic DFT to the problem of generation of high-energy electrons in nanocrystals with hot spots [5,6]. (4) Many-body interactions between excitons, plasmons and phonons in nano-assemblies should be treated using theoretical methods of quantum optics and give rise to quantum interference effects observed as Fano transparency windows [7,8]. [1] A. Kuzyk, R. Schreiber, Z. Fan, G. Pardatscher, E.-M. Roller, A. Högele, F. C. Simmel, A. O. Govorov, T. Liedl, Nature 483, 311 (2012). [2] A.Kuzyk, R. Schreiber, H. Zhang, A.O. Govorov, T. Liedl, Na Liu, Nature Materials 13, 862 (2014). [3] C. E. Rowland, I. Fedin, H. Zhang, S.K. Gray, A.O. Govorov, D.V. Talapin, and R.D.Schaller, Nature Materials 14, 484 (2015). [4] A.O. Govorov, H. Zhang, V. Demir, and Y.K. Gun'ko, Nano Today 9, 85 (2014); A.O. Govorov and H. Zhang, J. Phys. Chem. C, 119, 6181 (2015). [5] H. Harutyunyan, A. B. F. Martinson, D. Rosenmann, L.K. Khorashad, A.O.Govorov, and G.P. Wiederrecht, Nature Nanotechnology, online (2015). [6] W. Li, Z. J. Coppens, L. Vazquez, W. Wang, A. O. Govorov, J. Valentine, Nature Communications, accepted. [7] W. Zhang, G. W. Bryant, A. O. Govorov, Phys. Rev. Lett. 97, 146804 (2006). [8] M. L. Kerfoot, A.O. Govorov, D. Lu, R. J. O. Babaoye, Y. N. Gad, C. Czarnocki, M. Tsukamoto, A. S. Bracker, D. Gammon, and M. Scheibner, Nature Communications 5, 3299 (2014).

Last modified: Aug 24, 2015, 10:00:00 AM