Lars Gundlach, Associate Professor
University of Delaware
109 Lammot duPont Laboratory
Newark, DE 19716
Diploma in Physics, 2000, Free University of Bremen; Ph.D., 2005, Free University of Berlin; Postdoctoral, 2006-2011, Rutgers University
The prospect that nanoscience will provide solutions for some of the world's most urgent challenges, such as new non-fossil energy resources, non-silicon based electronics, novel drug delivery techniques, etc., demands a detailed understanding of dynamic processes on the nanoscale. Transport of energy is the most important process determining the evolution of a system. Especially the transport of charge carriers is essential for processes as fundamental as photosynthesis, catalytic chemistry, and of course all electronic applications. Energy transport on the nanoscale occurs on an ultra-short time scale. We are studying energy transport reactions in real time by employing novel time-resolved spectroscopic and microscopic techniques, simultaneously resolving nanoscale dimensions and femtosecond (10-15 s) dynamics. The necessary experimental techniques are developed and improved in our group.
Electron Transfer Reactions at Interfaces
Electron injection from a molecular donor orbital into empty electronic acceptor states of a solid is often referred to as heterogeneous electron transfer (HET). HET is of great significance in many different contexts ranging from condensed matter physics to biology. Since more than two decades there has been a continuing effort towards developing the field of molecular electronics, where HET will play a key role. HET has been studied in nano-hybrid systems aiming at practical applications like solar-cells. Since HET reveals unique properties of the electron transfer process, it can be considered also as a research topic in its own right. We are employing and developing ultrafast time-resolved techniques to study HET in real time and gain direct access to parameters governing the transfer reaction.
Charge Carrier Dynamics in Nanomaterials
Measurements that are performed on a large ensemble of particles demand a high degree of homogeneity to gain meaningful results. A better way of reducing the effect of broad distributions in sample properties is by monitoring single particles, or measuring single molecules. To achieve this, we developed an ultrafast time-resolved Kerr-gated fluorescence microscope. Application of this technique to charge carrier dynamics in CdSSe semiconductor nanowires let to a detailed understanding of the underlying dynamics that was formerly hidden in the ensemble average. We are improving and expanding this technique and applying it to a wide range of technological important materials.
- B. Abraham, J. Nieto-Pescador, L. Gundlach, “Ultrafast Relaxation Dynamics of Photoexcited Zinc-porphyrin: Electronic-vibrational Coupling,”
Journal of Physical Chemistry Letters, (2016) 7, 3151
- Z. Li, J. Nieto-Pescador, A. Carson, J. Blake, L. Gundlach, “Efficient Z-scheme Charge Separation in Novel Vertically-aligned ZnO/CdSSe Nanotrees,”
- J. Nieto-Pescador, B. Abraham, Z. Li, A. Batarseh, R. A. Bartynski, E. Galoppini, L. Gundlach, ”Heterogeneous Electron-Transfer Dynamics through Dipole-Bridge Groups,”
Journal of Physical Chemistry C, (2016)
- J. Nieto-Pescador, B. Abraham, A. J. Pistner, J. Rosenthal, L. Gundlach, “Electronic State Dependence of Heterogeneous Electron Transfer: Injection from the S1 and S2 State of Phlorin into TiO2,” Physical Chemistry Chemical Physics, (2015)
- J. Nieto-Pescador, B. Abraham, L. Gundlach, “Photo-induced Ultrafast Heterogeneous Electron Transfer at Molecule-Semiconductor Interfaces,”
Journal of Physical Chemistry Letters, (2014)
- L. Gundlach, F. Willig, “Ultrafast photoinduced electron transfer at electrodes: the general case of a heterogeneous electron transfer reaction,” ChemPhysChem, (2012) 13, 2877
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