A5057920276- Spectroscopy and Quantum Chemical Studies
- Photoreceptor and optogenetics research
- Perovskite Materials and Applications
- Advancements in Battery Materials
- Advanced Fluorescence Microscopy Techniques
- Advanced Battery Technologies Research
- Advanced Chemical Physics Studies
- Molecular Junctions and Nanostructures
- Spectroscopy Techniques in Biomedical and Chemical Research
- Organic Electronics and Photovoltaics
- Advanced Battery Materials and Technologies
- Photosynthetic Processes and Mechanisms
- Quantum Dots Synthesis And Properties
- Photochemistry and Electron Transfer Studies
- Photonic and Optical Devices
- Laser-Matter Interactions and Applications
- Strong Light-Matter Interactions
- Molecular spectroscopy and chirality
- Electron and X-Ray Spectroscopy Techniques
- Advanced Memory and Neural Computing
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- CO2 Reduction Techniques and Catalysts
- Electrochemical Analysis and Applications
- Radical Photochemical Reactions
University of Cambridge
2019-2024
Harvard University
2018-2022
University of Oxford
2012-2022
The Faraday Institution
2021-2022
Cavendish Hospital
2021
Friedrich Schiller University Jena
2009-2010
Leibniz Institute of Photonic Technology
2009-2010
Helmholtz Institute Jena
2009
Electrodeposited manganese oxide films are promising catalysts for promoting the oxygen evolution reaction (OER), especially in acidic solutions. The activity of these is known to be enhanced by introduction Mn3+ We present situ electrochemical and X-ray absorption spectroscopic studies, which reveal that may introduced into MnO2 an electrochemically induced comproportionation with Mn2+ persists OER active films. Extended fine structure (EXAFS) spectra Mn3+-activated indicate a decrease Mn-O...
A reaction cycle for redox-mediated, Ni-catalyzed aryl etherification is proposed under both photoredox and electrochemically mediated conditions. We demonstrate that a self-sustained Ni(I/III) operative in cases by chemically synthesizing characterizing common paramagnetic Ni intermediate establishing its catalytic activity. Furthermore, deleterious pathways leading to off-cycle Ni(II) species have been identified, allowing us discover optimized conditions achieving reactivity at ∼15-fold...
Simultaneous transport and coupling of ionic electronic charges is fundamental to electrochemical devices used in energy storage conversion, neuromorphic computing bioelectronics. While the mixed conductors enabling these technologies are widely used, dynamic relationship between generally poorly understood, hindering rational design new materials. In semiconducting electrodes, doping assumed be limited by motion ions due their large mass compared electrons and/or holes. Here, we show that...
Abstract The coupling of excitons in π-conjugated molecules to high-frequency vibrational modes, particularly carbon–carbon stretch modes (1,000–1,600 cm −1 ) has been thought be unavoidable 1,2 . These accelerate non-radiative losses and limit the performance light-emitting diodes, fluorescent biomarkers photovoltaic devices. Here, by combining broadband impulsive spectroscopy, first-principles modelling synthetic chemistry, we explore exciton–vibration a range molecules. We uncover two...
Iron hangman porphyrins with phenol, guanidinium, and sulfonic acid proton donor groups placed above the Fe porphyrin platform reduce CO2 to CO Faradaic efficiencies >93%. Computations show that activation of at center is enhanced by hanging group. Intramolecular hydrogen bonding from phenol guanidinium results in a 2.1–6.6 kcal/mol stabilization within pocket; sulfonate group deprotonated, thus resulting destabilization adduct due unfavorable electrostatic interactions. Electrochemical...
We present an experimental setup for recording vibrational coherences and thereby Raman spectra of molecules in their ground excited electronic states over the 50–3000 cm–1 spectral range using broadband impulsive spectroscopy. Our approach relies on combination a <10 fs excitation pulse with uncompressed white light continuum probe, which drastically reduces complexity compared to frequency domain based techniques. discuss parameters determining coherence amplitudes, outline how optimize...
Understanding how lithium-ion dynamics affect the (de)lithiation mechanisms of state-of-the-art nickel-rich layered oxide cathodes is crucial to improve electrochemical performance. Here, we directly observe two distinct kinetically induced lithium heterogeneities within single-crystal LiNixMnyCo(1−x−y)O2 (NMC) particles using recently developed operando optical microscopy, challenging notion that uniform occurs individual particles. Upon delithiation, a rapid increase in diffusivity at...
Abstract Crystallographic phase engineering plays an important part in the precise control of physical and electronic properties materials. In two-dimensional transition metal dichalcogenides (2D TMDs), using chemical lithiation with organometallization agent n -butyllithium ( -BuLi), to convert semiconducting 2H (trigonal) metallic 1T (octahedral) phase, has been widely explored for applications areas such as transistors, catalysis batteries 1–15 . Although this can be performed at ambient...
Conical intersections play a crucial role in photochemical processes, but limited experimental information exists on the structural distortions that couple electronic with reactive nuclear motion. Using ultra-broadband and highly time-resolved optical spectroscopy, we follow evolution of vibrational wavepackets after passage through conical intersection during primary visual event, 11-cis to all-trans photoisomerization retinal chromophore rhodopsin. Comparison coherences generated under...
The quantum efficiency in photoredox catalysis is the crucial determinant of energy intensity and, thus, intrinsically tied to sustainability overall process. Here, we track formation different transient species a catalytic hydroamidation reaction initiated by an Ir(III) photoexcited complex with 2-cyclohexen-1-yl(4-bromophenyl)carbamate. We find that back between amidyl radical and Ir(II) photoproducts generated from quenching leads low system. Using absorption spectroscopy, all rate...
We introduce femtosecond wide-field transient absorption microscopy combining sub-10 fs pump and probe pulses covering the complete visible (500–650 nm) near-infrared (650–950 spectrum with diffraction-limited optical resolution. demonstrate capabilities of our system by reporting spatially- spectrally-resolved electronic response MAPbI3–xClx perovskite films reveal significant quenching bleach signal at grain boundaries. The unprecedented temporal resolution enables us to directly observe...
Abstract The complex dynamics of ultrafast photoinduced reactions are governed by their evolution along vibronically coupled potential energy surfaces. It is now often possible to identify such processes, but a detailed depiction the crucial nuclear degrees freedom involved typically remains elusive. Here, combining excited-state time-domain Raman spectroscopy and tree-tensor network state simulations, we construct full 108-atom molecular movie singlet fission in pentacene dimer, explicitly...
Coupling of nuclear and electronic degrees freedom mediates energy flow in molecules after optical excitation. The associated coherent dynamics polyatomic systems, however, remain experimentally unexplored. Here, we combined transient absorption spectroscopy with population control to reveal wave packet during the ${S}_{2}\ensuremath{\rightarrow}{S}_{1}$ internal conversion $\ensuremath{\beta}$-carotene. We show that passage through a conical intersection is vibrationally thereby provides...
Strong-coupling between excitons and confined photonic modes can lead to the formation of new quasi-particles termed exciton-polaritons which display a range interesting properties such as super-fluidity, ultrafast transport Bose-Einstein condensation. typically occurs when an excitonic material is confided in dielectric or plasmonic microcavity. Here, we show polaritons form at room temperature chemically diverse, organic semiconductor thin films, despite absence external cavity. We find...
We present a novel optical transient absorption and reflection microscope based on diffraction-limited pump pulse in combination with wide-field probe pulse, for the spatio-temporal investigation of ultrafast population transport thin films. The achieves temporal resolution down to 12 fs simultaneously provides sub-10 nm spatial accuracy. demonstrate capabilities by revealing an excited-state exciton up 32 film pentacene tracking carrier motion p-doped silicon. use few-cycle excitation...
Optical pump-probe spectroscopy is a powerful tool for the study of non-equilibrium electronic dynamics and finds wide applications across range fields, from physics chemistry to material science biology. However, shortcoming conventional that photoinduced changes in transmission, reflection scattering can simultaneously contribute measured differential spectra, leading ambiguities assigning origin spectral signatures ruling out quantitative interpretation spectra. Ideally, these methods...
Extensive worldwide efforts have been made to understand the degradation behavior of layered Ni-rich LiNixMnyCo(1−x−y)O2 (NMC) cathodes. The majority studies carried out date focused on thermodynamic perspectives...
How molecules convert light energy to perform a specific transformation is fundamental question in photophysics. Ultrafast spectroscopy reveals the kinetics associated with electronic flow, but little known about how absorbed photon drives nuclear or motion. Here, we used ultrabroadband transient absorption monitor coherent vibrational flow after photoexcitation of retinal chromophore. In proton pump bacteriorhodopsin observed activation hydrogen wagging and backbone torsional modes that...
Channelrhodopsins are light-gated ion channels with extensive applications in optogenetics. Channelrhodopsin-1 from Chlamydomonas augustae (CaChR1) exhibits a red-shifted absorption spectrum as compared to Channelrhodopsin-2, which is highly beneficial for optogenetic application. The primary event the photocycle of CaChR1 involves an isomerization protein-bound retinal chromophore. Here, we apply time-resolved vibronic spectroscopy reveal electronic and structural dynamics associated first...