It is crucial for photovoltaics and other technical applications, how efficiently energy spreads in a small volume. With new methods, the path of energy in the nanometer range can now be followed precisely.
Plants and bacteria lead the way: They can capture the energy of sunlight with light-harvesting antennas and transfer it to a reaction centre. Transporting energy efficiently and in a targeted fashion in a minimum of space – this is also of interest to mankind. If scientists were to master it perfectly, they could significantly improve photovoltaics and optoelectronics.
Two new spectroscopic methods
But how can the flow of energy be observed? This is what Tobias Brixner's group at the Institute of Physical and Theoretical Chemistry at Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany, is working on.
In the journal Nature Communications, the team now presents two new spectroscopic methods with which energy transport on the nanoscale can be observed. According to the JMU professor, the new findings provide valuable information for the design of artificial light-harvesting antennas.
These research successes were achieved in cooperation with the working groups of Christoph Lambert and Todd Marder (JMU Würzburg), Uwe Bunz and Andreas Dreuw (University of Heidelberg) as well as Jasper Knoester and Maxim Pshenichnikov (University of Groningen, Netherlands).
Nanotubes imitate nature
Using the new methods, the research teams have succeeded in deciphering the energy transport in double-walled nanotubes made up of thousands of dye molecules. These tiny tubes serve as models for the light-harvesting antennas of photosynthetically active bacteria.
At low light intensities, the energetic excitations are transported from the outer to the inner wall of the tubes. At high intensities, on the other hand, the excitations only move along the outer wall – if two excitations meet there, one of them disappears. "This effect, which has been known for some time, can be made directly visible with our method for the first time," says Brixner.
The measurements could be carried out by combining the exciton-exciton-interaction-two-dimensional spectroscopy (EEI2D spectroscopy) method developed in the Brixner group with a microfluidic arrangement of the Groningen group.
Data acquisition is much faster
In the second paper, the research teams also demonstrate a new approach to measuring energy flows. The highlight: The speed of the data recording could be extremely increased compared to the state of the art. Within just eight minutes, it was possible to measure up to 15 different 3D spectra simultaneously in a single experiment. Traditional methods, on the other hand, typically require several hours for only a single spectrum.
As a basis for measuring coherent spectra over three frequency dimensions, the researchers employed a fast method of varying the temporal sequence of ultrashort laser pulses. "The expansion from 2D to 3D frequency analysis and the increase in the number of light-matter interactions from the four usual in the literature to six now provides detailed insights into the dynamics of highly excited states," says Brixner.
This work was funded by the Solar Technologies Go Hybrid research network of the Free State of Bavaria, the German Research Foundation (DFG), and the European Research Council (ERC) as part of the ERC consolidator grant "MULTISCOPE".
Prof. Dr. Tobias Brixner, Institute of Physical and Theoretical Chemistry, JMU Würzburg, firstname.lastname@example.org
S. Mueller, J. Lüttig, P. Malý, L. Ji, J. Han, M. Moos, T. B. Marder, U. H. F. Bunz, A. Dreuw, C. Lambert, and T. Brixner, “Rapid multiple‐quantum three‐dimensional fluorescence spectroscopy disentangles quantum pathways”, Nature Communications, https://doi.org/10.1038/s41467-019-12602-x (2019)
B. Kriete, J. Lüttig, T. Kunsel, P. Malý, T. L. C. Jansen, J. Knoester, T. Brixner, and M. S. Pshenichnikov, “Interplay between structural hierarchy and exciton diffusion in artificial light harvesting”, Nature Communications, https://doi.org/10.1038/s41467-019-12345-9 (2019)
http://www.phys-chemie.uni-wuerzburg.de/en/arbeitsgruppen/prof-dr-tobias-brixner... Webseite Prof. Tobias Brixner
Robert Emmerich | Julius-Maximilians-Universität Würzburg
New laser opens up large, underused region of the electromagnetic spectrum
15.11.2019 | Harvard John A. Paulson School of Engineering and Applied Sciences
NASA sending solar power generator developed at Ben-Gurion U to space station
15.11.2019 | American Associates, Ben-Gurion University of the Negev
The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...
Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.
New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...
If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.
Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...
Quantum-based communication and computation technologies promise unprecedented applications, such as unconditionally secure communications, ultra-precise...
In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.
An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort...
15.11.2019 | Event News
15.11.2019 | Event News
05.11.2019 | Event News
15.11.2019 | Power and Electrical Engineering
15.11.2019 | Power and Electrical Engineering
15.11.2019 | Ecology, The Environment and Conservation