A5030306237- Photochemistry and Electron Transfer Studies
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Photosynthetic Processes and Mechanisms
- Photoreceptor and optogenetics research
- Free Radicals and Antioxidants
- Spectroscopy and Laser Applications
- Atmospheric chemistry and aerosols
- Quantum Dots Synthesis And Properties
- Carbon and Quantum Dots Applications
- Molecular Spectroscopy and Structure
- DNA and Nucleic Acid Chemistry
- Atmospheric Ozone and Climate
- Advanced biosensing and bioanalysis techniques
- Particle Accelerators and Free-Electron Lasers
- Geological formations and processes
- Electrochemical Analysis and Applications
- Nanocluster Synthesis and Applications
- Porphyrin and Phthalocyanine Chemistry
- Hydrocarbon exploration and reservoir analysis
- Molecular spectroscopy and chirality
- High-pressure geophysics and materials
- Diamond and Carbon-based Materials Research
- Spectroscopy and Chemometric Analyses
- Force Microscopy Techniques and Applications
University of Bristol
2016-2025
Engineering and Physical Sciences Research Council
2023
Cardiff University
2023
Research Complex at Harwell
2023
Southmead Hospital
2023
Université Libre de Bruxelles
2020
Center for Functional Nanomaterials
2018
Google (United States)
2018
Lawrence Berkeley National Laboratory
2013-2016
Kavli Energy NanoScience Institute
2015-2016
Significance To have a full understanding of the role nuclear motions involved in nonradiative relaxation dynamics complex molecular systems such as carotenoids, nanomaterials, and photoswitches, ability to correlate electronic degrees freedom is imperative. We developed 2D electronic–vibrational spectroscopy observe this correlation, new spectroscopic technique will provide direct probe coupling between at conical intersections, thus underlying mechanisms driving ensuing photochemistry.
High-resolution time-of-flight measurements of H atom products from photolysis phenol, 4-methylphenol, 4-fluorophenol, and thiophenol, at many UV wavelengths (lambda(phot)), have allowed systematic study the influence ring substituents heteroatom on fragmentation dynamics. All dissociate by X-H (X = O, S) bond fission after excitation their respective S(1)((1)pipi*)-S(0) origins all shorter wavelengths. The achieved kinetic energy resolution reveals population selected vibrational levels...
When phenol is photoexcited to its S(1) (1(1)ππ∗) state at wavelengths in the range 257.403 ≤ λ(phot) 275.133 nm O-H bond dissociates yield an H atom and a phenoxyl co-product, with available energy shared between translation well characterised product vibration. It accepted that dissociation enabled by transfer S(2) (1(1)πσ∗) state, for which potential surface (PES) repulsive stretch coordinate, R(O-H). This PES cut near R(O-H) = 1.2 Å S(0) ground 2.1 Å, give two conical intersections...
The photochemical dynamics of three classes organic photoredox catalysts employed in organocatalyzed atom-transfer radical polymerization (O-ATRP) are studied using time-resolved optical transient absorption and fluorescence spectroscopy. nine selected for study examples N-aryl core-substituted dihydrophenazine, phenoxazine phenothiazine compounds with varying propensities control outcomes. Excited singlet-state lifetimes extracted from the spectroscopic measurements reported...
Abstract Computational protein design is advancing rapidly. Here we describe efficient routes starting from validated parallel and antiparallel peptide assemblies to two families of α-helical barrel proteins with central channels that bind small molecules. designs are seeded by the sequences structures defined de novo oligomeric barrel-forming peptides, adjacent helices connected loop building. For targets helices, short loops sufficient. However, require longer connectors; namely, an outer...
Organic cation rotation in hybrid organic-inorganic lead halide perovskites has previously been associated with low charge recombination rates and (anti)ferroelectric domain formation. Two-dimensional infrared spectroscopy (2DIR) was used to directly measure 470 ± 50 fs 2.8 0.5 ps time constants the reorientation of formamidinium cations (FA+, NH2CHNH2+) iodide perovskite thin films. Molecular dynamics simulations reveal FA+ agitates about an equilibrium position, NH2 groups pointing at...
Abstract The polymorphic nature of G‐quadruplex (G4) DNA structures points to a range potential applications in nanodevices and an opportunity control G4 biological settings. Light is attractive means for the regulation oligonucleotide structure as it can be delivered with high spatiotemporal precision. However, surprisingly little attention has been devoted towards development ligands that allow photoregulation folding. We report novel G4‐binding chemotype derived from stiff‐stilbene....
Solvent collisions can often mask initial disposition of energy to the products solution-phase chemical reactions. Here, we show with transient infrared absorption spectra obtained picosecond time resolution that nascent HCN reaction CN radicals cyclohexane in chlorinated organic solvents exhibit preferential excitation one quantum C-H stretching mode and up two quanta bending mode. On scales approximately 100 300 picoseconds, undergo relaxation vibrational ground state by coupling solvent...
This article reports a comprehensive study of the mechanisms H atom loss in aniline (C6H5NH2) following ultraviolet excitation, using (Rydberg) photofragment translational spectroscopy. N–H bond fission via low lying π1σ∗ electronic state is experimentally demonstrated. The potential energy surface (PES) this prototypical aromatic amine essentially repulsive along stretch coordinate, but possesses shallow well vertical Franck–Condon region, supporting quasibound vibrational levels....
To explore how the solvent influences primary aspects of bond breaking, gas and solution phase photochemistries phenol para-methylthiophenol are directly compared using, respectively, H (Rydberg) atom photofragment translation spectroscopy femtosecond transient absorption spectroscopy. Approaches demonstrated that allow explicit comparisons nascent product energy disposals dissociation mechanisms in two phases. It is found, at least for case weakly perturbing cyclohexane environment, most...
This article explores the extent to which insights gleaned from detailed studies of molecular photodissociations in gas phase (i.e. under isolated molecule conditions) can inform our understanding corresponding photofragmentation processes solution. Systems selected for comparison include a thiophenol (p-methylthiophenol), thioanisole (p-methylthioanisole) and phenol, vacuum cyclohexane UV excitation results RX–Y (X = O, S; Y H, CH3) bond fission all cases, but over timescales that vary by...
Light-harvesting complex II (LHCII) serves a central role in light harvesting for oxygenic photosynthesis and is arguably the most important photosynthetic antenna complex. In this work, we present two-dimensional electronic-vibrational (2DEV) spectra of LHCII isolated from spinach, demonstrating possibility using technique to track transfer electronic excitation energy between specific pigments within We assign spectral bands via comparison with 2DEV chromophores, chlorophyll b, evidence...
The excited state dynamics of phenol in water have been investigated using transient absorption spectroscopy. Solvated electrons and vibrationally cold phenoxyl radicals are observed upon 200 267 nm excitation, but with formation time scales that differ by more than 4 orders magnitude. impact these findings is assessed terms the relative importance autoionization versus proton-coupled electron transfer mechanisms this computationally tractable model system.
Summary From global food security to textile production and biofuels, the demands currently made on plant photosynthetic productivity will continue increase. Enhancing photosynthesis using designer, green sustainable materials offers an attractive alternative current genetic‐based strategies promising work with nanomaterials has recently started emerge. Here we describe in planta use of carbon‐based nanoparticles produced by low‐cost renewable routes that are bioavailable mature plants....
The electron-conducting circuitry of life represents an as-yet untapped resource exquisite, nanoscale biomolecular engineering. Here, we report the characterization and structure a de novo diheme "maquette" protein, 4D2, which subsequently use to create expanded, modular platform for heme protein design. A well-folded monoheme variant was created by computational redesign, then utilized experimental validation continuum electrostatic redox potential calculations. This demonstrates how...
The dissociation dynamics of gas phase phenol-d(5) molecules (C(6)D(5)OH) following excitation at numerous wavelengths in the range 275 > or = lambda(phot) 193.3 nm have been investigated using techniques H (Rydberg) atom photofragment translational spectroscopy and resonance enhanced multiphoton ionization spectroscopy. results are compared with those from recent studies fully hydrogenated deuterated isotopologues (C(6)H(5)OH C(6)D(5)OD), various halo- methyl-substituted phenols. Analysis...
Two-dimensional electronic-vibrational (2DEV) spectroscopy is an experimental technique that shows great promise in its ability to provide detailed information concerning the interactions between electronic and vibrational degrees of freedom molecular systems. The physical quantities 2DEV particularly suited for measuring have not yet been fully determined, nor how these effects manifest spectra. In this work, we investigate use center line slope a peak spectrum as measure both dynamic...
Ultrafast transient electronic absorption, one- and two- dimensional electronic-vibrational spectroscopies were used to study the nonradiative relaxation dynamics of β-apo-8'-carotenal (bapo), a model aldehyde containing carotenoid, in cyclohexane acetonitrile solutions. 2D (2DEV) spectroscopy allows for direct correlation between intrinsically coupled vibrational degrees freedom, which are thought play an important role driving bapo from bright S2 lower-lying dark S1 state. Line shapes...
The development of robust and reproducible synthetic strategies for the production carbon dots (CDs) with improved fluorescence quantum yields distinct emission profiles is great relevance given vast range applications CDs. fundamental understanding at a molecular level their formation mechanism, chemical structure how these parameters are correlated to photoluminescence (PL) properties thus essential. In this study, we describe synthesis structural characterization CDs physico-chemical...