Our goal is to understand the fundamental physical phenomena underlying chemical reactions and the transport of charges and energy. This understanding will enable cheaper and more environmentally benign materials for solar-energy harvesting, new insights in the mechanisms for photocatalysis, and new functional materials such as batteries.
Using optical laser pulses or electrical fields as triggers, we can take snapshots and make “Molecular Movies” of the structural dynamics response of functional materials with powerful X-ray pulses from large-scale X-ray facilities such as synchrotrons and X-ray Free Electron lasers.
Current activities
Currently, our scientific focus is on the dynamics of photo-active chemical compounds in solution, with a special emphasis on novel materials for solar energy harvesting. One key aspect of this research is to understand how photo-excited electrons in molecules experience and influence the potential energy landscape that govern how well suited a certain compound may be for solar energy applications. However, such molecules do not exist in isolation, and the surrounding solvent medium may directly influence the photochemical reactions and another current avenue of research is therefore the solute-solvent interactions, also known as “solvation”.
Our research is focused on the following projects
Studying what fundamental structural properties and dynamics determine charge mobility in next-gen battery materials (ERC RIA ULTRA-BAT project, 2023-2027, https://ultrabat.dtu.dk
Measuring and understanding the interplay between electronic and structural dynamics in materials for efficient solar energy harvesting via the singlet-fission phenomenon. (DFF ULTRA-SOL project, 2022-2026)
Understanding how the most ubiquitous of all solvents, water, influences chemical reactions at the molecular level and in real-time (NNF NERD project, 2020-2027)
Method development, both in terms of experiments and in terms of new methods for data reduction and data analysis of terabyte-sized data sets with sub-picosecond time resolution.
People
In the Ultrafast group we value both teamwork and independence extremely high, both when we go to work for 100 hours straight at a synchrotron and when we travel to conferences. We strive for everyone in our group to take responsibility for their own project, while at the same time contributing with key skills to other projects. Whenever possible, we travel to beamtimes and conferences as a group to maximize our impact, and to strengthen our social cohesion.
Current people in the Ultrafast Group:
Prof. Martin Meedom Nielsen
Asc. Prof. Kristoffer Haldrup
Research Engineer (software), Asmus O. Dohn
Prof. Klaus B. Møller (at DTU Chemistry)
Morten Haubro (Postdoc, ULTRA-SOL and ULTRA-BAT)
Kerstin Mitterer (PhD Student, ULTRA-SOL)
Benedikte Jensen (PhD student, ULTRA-SOL at DTU Chemistry)
Oliver Ohlson (PhD Student, NERD project)
Martha Wachter-Lehn (PhD Student, ULTRA-BAT)
Recent Alumni:
Bianca Hansen (PhD from NERD, now Data Scientist at Tryg Insurance)
Verena Markmann (Postdoc on NERD, now postdoc at HAW Hamburg)
Jaysree Pan (Postdoc on NERD, now Researcher at DTU Energy)
Magnus Christiansen (MSc Thesis student, now PhD student at University of Iceland)
Amke Nimmrich (Guest PhD, now Postdoc at University of Washington)
Philipp Lenzen (PhD student, now Postdoc at Stanford/PULSE, California)
Christoffer Egeberg (MSc Thesis student, now R&D Engineer at Synopsis, Denmark).
Experimental activities
Large-scale X-ray facilities allows us to combine:
• The atomic resolution of X-ray scattering with
• The sensitivity to electronic states delivered by X-ray spectroscopy.
At synchrotron X-ray sources we combine the superior average brilliance, high stability and high-energy X-rays to enable high-resolution studies down to time scales of picoseconds. At X-ray free Electron Lasers we take advantage of the incredibly high peak brilliance to study the dynamics of atoms and molecules down to time scales of only a few tens of femtoseconds. We are currently involved in investigations utilizing the following facilities:
• The ESRF synchrotron in Grenoble, France, (link)
• The APS synchrotron near Chicago, USA, (link)
• The LCLS X-ray Free Electron Laser at Stanford, USA, (link)
• The SACLA X-ray Free Electron Laser in Japan, (link)
• The EuXFEL in Hamburg, Germany (link)
• SwissFEL near Zurich, Switzerland (link)
Theory and Simulations
In order to interpret the many TBs of incredibly highly resolved X-ray data which we obtain though our experimental activities, we also need a solid theoretical framework. In our group we currently focus on
- Algebraic methods for data reduction and interpretation
- Methods for directly connecting simulation results with experimental data
But we also utilize the tools of computational chemistry such as
- Classical Molecular Dynamics (MD)
- Density Functional Theory (DFT) calculations, and hybrids such as
- QM/MM or AIMD, combining DFT with MD
Student projects
We always welcome motivated students, all the way from 1st year project to the PhD level! Such projects can be highly tailored to match the interests and skills of the student to our research activities, and we have projects focused on simulation, experiments and data analysis. If you wish to work with us, then drop by or send us an email!
Recent and current student projects have covered such diverse topics as:
- Benchmarking an energy-resolving detector for structural studies of self-assembled molecular wires
- Analysing time-resolved optical data on isomerizing molecules
-Almost all of our activities rely to one degree or another on Python programming, so if you are not familiar with Python already, a project with our group will for sure make you an experienced user of this versatile programming tool.
Collaborations
All of our work is highly interdisciplinary in scope, and we therefore always collaborate with both national and international partners, both at universities and at large-scale facilities. Our current collaboration partners include
- The Theoretical Chemistry group of Prof. K.B. Møller at DTU Chemistry
- Group of Jens Wenzel Andreasen, DTU Energy (Materials, characterization)
- The Chemical Physics group at Lund University (Materials, laser characterization)
- The FXE group at the European XFEL (Instrumentation)
- G. Levi Group, University of Iceland (theory)
- Gonzales/Mai Group in Vienna (theory)
- The group of G. Vanko at RFKI in Budapest, Hungary (Materials, laser characterization)
- Prof. Lin X. Chen at Northwestern University/Advanced Photon Source
- The Gaffney/Cordones-Hahn groups at PULSE, Stanford, USA