A5007991694- Spectroscopy and Quantum Chemical Studies
- Photosynthetic Processes and Mechanisms
- Photoreceptor and optogenetics research
- Organic Electronics and Photovoltaics
- Laser-Matter Interactions and Applications
- Mass Spectrometry Techniques and Applications
- Molecular Junctions and Nanostructures
- Advanced Fiber Laser Technologies
- Conducting polymers and applications
- Molecular spectroscopy and chirality
- Advanced Fluorescence Microscopy Techniques
- Quantum, superfluid, helium dynamics
- Perovskite Materials and Applications
- Advanced Chemical Physics Studies
- Mechanical and Optical Resonators
- Electrochemical Analysis and Applications
- Advanced Sensor and Energy Harvesting Materials
- Analytical Chemistry and Sensors
- solar cell performance optimization
- Advanced biosensing and bioanalysis techniques
- Laser Material Processing Techniques
- Electron Spin Resonance Studies
- Porphyrin and Phthalocyanine Chemistry
- Marine and coastal ecosystems
- Photochemistry and Electron Transfer Studies
University of Cambridge
2019-2023
Lund University
2012-2021
Charles University
2013-2021
University of Gothenburg
2019-2021
University of Zurich
2018
Getinge (Sweden)
2013-2017
NOAA Chemical Sciences Laboratory
2015
Precisely tuning an organic semiconductor’s crystalline order allows exciton transport to proceed 2-3 orders of magnitude faster.
Abstract Natural and artificial light-harvesting processes have recently gained new interest. Signatures of long-lasting coherence in spectroscopic signals biological systems been repeatedly observed, albeit their origin is a matter ongoing debate, as it unclear how the loss due to interaction with noisy environments such averted. Here we report experimental theoretical verification coherent exciton–vibrational (vibronic) coupling an light harvester, molecular J-aggregate. In this...
Photosynthetic reaction centers convert sunlight into a transmembrane electrochemical potential difference, providing chemical energy to almost all life on earth. Light is efficiently transferred through chromophore cofactors the sites, where charge separation occurs. We applied two-dimensional electronic spectroscopy assess role of coherences in photoresponse bacterial center Rhodobacter sphaeroides. By controlling polarization laser beams, we were able assign unambiguously oscillatory...
Organic solar cells based on non-fullerene acceptors can show high charge generation yields despite near-zero donor-acceptor energy offsets to drive separation and overcome the mutual Coulomb attraction between electron hole. Here, we use time-resolved optical spectroscopy that free charges in these systems are generated by thermally activated dissociation of interfacial charge-transfer states occurs over hundreds picoseconds at room temperature, three orders magnitude slower than comparable...
Observation of coherence shifts reveals hot energy transfer and excess dissipation mechanisms in photosynthesis.
The vibrational dynamics of Pt–H on a nanostructured platinum surface has been examined by ultrafast infrared spectroscopy. Three bands are observed at 1800, 2000, and 2090 cm–1, which assigned to Pt–CO in bridged linear configuration Pt–H, respectively. Lifetime analysis revealed time constant (0.8 ± 0.1) ps for the mode, considerably shorter than that because its stronger coupling metal substrate. Two-dimensional attenuated total reflection spectroscopy provided additional evidence...
Singlet fission (SF), an exciton-doubling process observed in certain molecular semiconductors where two triplet excitons are generated from one singlet exciton, requires correctly tuned intermolecular coupling to allow separation of the triplets different units. We explore this using DNA-encoded assembly SF-capable pentacenes into discrete π-stacked constructs defined size and geometry. Precise structural control is achieved via a combination DNA duplex formation between complementary...
We measure spectrally and spatially resolved high-order harmonics generated in argon using chirped multi-cycle laser pulses. Using a stable, high-repetition rate we observe detailed interference structures the far-field. The are of two kinds; off-axis from long trajectory only on-axis including short trajectories. former is readily visible far-field spectrum, modulating both spectral spatial profile. To access latter, vary chirp fundamental, imparting different phases on trajectories,...
Two-dimensional electronic spectroscopy, and especially the polarization-controlled version of it, is cutting edge technique for disentangling various types coherences in molecules molecular aggregates. In order to evaluate coherences, which often decay on a 100 fs time scale, early population times have be included analysis. However, signals this region are typically plagued by several artifacts, unavoidable pulse overlap region. paper, we show that, case two-dimensional spectroscopy...
We generate high-order harmonics at high pulse repetition rates using a turnkey laser. High-order 400 kHz are observed when argon is used as target gas. In neon, we achieve generation of photons with energies exceeding 90 eV (∼13 nm) 20 kHz. measure photon flux up to 4.4 × 10(10) per second harmonic in 100 Many experiments employing would benefit from higher rates, and the user-friendly operation opens for applications coherent extreme ultra-violet pulses new research areas.
Abstract The sub-cycle dynamics of electrons driven by strong laser fields is central to the emerging field attosecond science. We demonstrate how can be probed through high-order harmonic generation, where different trajectories leading same order are initiated at times, thereby probing strengths. find large differences between with respect both their sensitivity driving ellipticity and resonant enhancement. To accurately describe dependence long trajectory harmonics we must include a...
Optical nonlinear spectroscopies carry a high amount of information about the systems under investigation; however, as they report polarization signals, resulting spectra are often congested and difficult to interpret. To recover landscape energy states physical processes such electron transfer, clear interpretation signals is prerequisite. Here, we focus on electrochromic band-shift signal, which generated when an internal electric field established in system following optical excitation....
Photosynthetic proteins have evolved over billions of years so as to undergo optimal energy transfer the sites charge separation. Based on spectroscopically detected quantum coherences, it has been suggested that this is partially wavelike. This conclusion critically depends assignment coherences evolution excitonic superpositions. Here we demonstrate for a bacterial reaction centre protein long-lived coherent spectroscopic oscillations, which bear canonical signatures superpositions, are...
Coherent phenomena have been widely suggested to play a role in efficient photosynthetic light harvesting and charge separation processes. To substantiate these ideas, of intramolecular vibrational coherences from purely electronic or mixed vibronic is essential. this end, polarization-controlled two-dimensional spectroscopy has shown provide an effective selectivity. We show that analogous discrimination can be achieved transient grating experiment by employing the double-crossed...
Organic solar cells (OSCs) based on non-fullerene acceptors can show high charge generation yields despite near-zero donor-acceptor energy offsets to drive separation and overcome the mutual Coulomb attraction between electron hole. Here we use time-resolved optical spectroscopy that free charges in these systems are generated by thermally activated dissociation of interfacial charge-transfer excitons (CTEs) occurs over hundreds picoseconds at room temperature, three orders magnitude slower...
Efficient energy transport is highly desirable for organic semiconductor (OSC) devices such as photovoltaics, photodetectors, and photocatalytic systems. However, photo-generated excitons in OSC films mostly occupy localized states over their lifetime. Energy hence thought to be mainly mediated by the site-to-site hopping of excitons, limiting exciton diffusion coefficients below ~10^{-2} cm^2/s with corresponding lengths ~50 nm. Here, using ultrafast optical microscopy combined...
We study how the two shortest quantum paths involved in high-order harmonic generation are affected by polarization of driving laser using a commercially available high repetition rate system.
Long-lived coherences have been observed in various biological complexes and their origin is debated. We used polarization-controlled 2D electronic spectroscopy to reveal a photophysical process of coherence shift, explaining bacterial reaction centers.