Excitons in complex molecular assemblies: localization, coherence and dynamics

Abstract

Self-assembled molecular systems play an important role in Nature as well as modern materials science. In particular, a wide variety of assemblies of dye molecules exist with interesting optical functionality, such as strong and tunable absorption and emission properties and ultrafast excitation energy transport. Nature uses such assemblies abundantly as highly efficient antenna systems in the photosynthetic apparatus of bacteria, algae, and higher plants and a quest is ongoing for biomimetic systems with similar or even better properties. The primary optical actors in such assemblies are Frenkel excitons, molecular excitations shared by a number of molecules. The detailed properties of the excitons result from a complex interplay between intermolecular excitonic interactions, exciton-vibration interactions, disorder, and interactions with a thermal bath. In this seminar, he will present recent theoretical as well as experimental (ultrafast spectroscopic) advances in this field. He will mainly focus on nanotubular molecular aggregates, but other examples may briefly be address as well. Red threads through the seminar will be the aspects of localization, coherence, and dynamics of the excitons. Ample comparison between theory and experiment will be presented.

Introduction

Jasper Knoester received his PhD in 1987 at the Institute for Theoretical Physics, University of Utrecht, The Netherlands. From 1987-1989 he was postdoc at the University of Rochester, NY, USA. In 1989 he received a Huygens Fellowship from the Netherlands Organization for Scientific Research (NWO) and he started his own line of research at the University of Groningen, The Netherlands, in the Department of Chemical Physics. In 1993 he was appointed as full professor of Theory of Condensed Matter Physics at this university, a position he has held till today.  In the academic year 2001-2002 Knoester was visiting professor at the Chemistry Department of MIT. From 2003-2009 he was Director of the Zernike Institute for Advanced Materials at the University of Groningen. The Zernike Institute has been a national center of excellence since 1999 and is a globally top-10 ranked center for materials science. Since 2010, Knoester has been Dean of the Faculty of Mathematics and Natural Sciences of the University of Groningen.

Jasper Knoester has (co)authored over 160 peer reviewed publications, with a total of more than 4200 citations and an h-index of 35. He has presented invited talks at over 90 international conferences and workshops. Since 2008, he has held a guest professorship at Jilin University in Changchun, China.