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2014, Dalton Trans.
Complex 1 exhibits a formally forbidden energy transfer from the metal-based triplet to the fluorescent Bodipy singlet state.
2011 •
Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics.
Proceedings of the Royal Society B: Biological Sciences
How to colour a flower: on the optical principles of flower colorationThe coloration of flowers is due to the wavelength-selective absorption by pigments of light backscattered by structures inside the petals. We investigated the optical properties of flowers using (micro)spectrophotometry and anatomical methods. To assess the contribution of different structures to the overall visual signal of flowers, we used an optical model, where a petal is considered as a stack of differently pigmented and structured layers and we interpreted the visual signals of the model petals with insect vision models. We show that the reflectance depends, in addition to the pigmentation, on the petal's thickness and the inhomogeneity of its interior. We find large between-species differences in floral pigments, pigment concentration and localization, as well as floral interior structure. The fractions of reflected and transmitted light are remarkably similar between the studied species, suggesting common selective pressures of pollinator visual systems. Our optical mod...
Journal of Raman Spectroscopy
Investigation of an unnatural amino acid for use as a resonance Raman probe: detection limits and solvent and temperature dependence of the νCN band of 4-cyanophenylalanine2008 •
Nature Materials
Exciton antennas and concentrators from core-shell and corrugated carbon nanotube filaments of homogeneous composition2010 •
There has been renewed interest in solar concentrators and optical antennas for improvements in photovoltaic energy harvesting and new optoelectronic devices. In this work, we dielectrophoretically assemble single-walled carbon nanotubes (SWNTs) of homogeneous composition into aligned filaments that can exchange excitation energy, concentrating it to the centre of core-shell structures with radial gradients in the optical bandgap. We find an unusually sharp, reversible decay in photoemission that occurs as such filaments are cycled from ambient temperature to only 357K, attributed to the strongly temperature-dependent second-order Auger process. Core-shell structures consisting of annular shells of mostly (6,5) SWNTs (Eg=1.21eV) and cores with bandgaps smaller than those of the shell (Eg=1.17eV (7,5)-0.98eV (8,7)) demonstrate the concentration concept: broadband absorption in the ultraviolet-near-infrared wavelength regime provides quasi-singular photoemission at the (8,7) SWNTs. This approach demonstrates the potential of specifically designed collections of nanotubes to manipulate and concentrate excitons in unique ways.
Scientific reports
Control of crystallographic orientation in diamond synthesis through laser resonant vibrational excitation of precursor molecules2014 •
Crystallographic orientations determine the optical, electrical, mechanical, and thermal properties of crystals. Control of crystallographic orientations has been studied by changing the growth parameters, including temperature, pressure, proportion of precursors, and surface conditions. However, molecular dynamic mechanisms underlying these controls remain largely unknown. Here we achieved control of crystallographic orientations in diamond growth through a joint experimental and theoretical study of laser resonant vibrational excitation of precursor molecules (ethylene). Resonant vibrational excitation of the ethylene molecules using a wavelength-tunable CO2 laser steers the chemical reactions and promotes proportion of intermediate oxide species, which results in preferential growth of {100}-oriented diamond films and diamond single crystals in open air. Quantum molecular dynamic simulations and calculations of chemisorption energies of radicals detected from our mass-spectroscop...
Light: Science & Applications
Ultraviolet laser photolysis of hydrocarbons for nondiamond carbon suppression in chemical vapor deposition of diamond films2010 •
The detection of circumstellar water vapour around the ageing carbon star IRC +10216 challenged the current understanding of chemistry in old stars, because water was predicted to be almost absent in carbon-rich stars. Several explanations for the water were postulated, including the vaporization of icy bodies (comets or dwarf planets) in orbit around the star, grain surface reactions, and photochemistry in the outer circumstellar envelope. With a single water line detected so far from this one carbon-rich evolved star, it is difficult to discriminate between the different mechanisms proposed. Here we report the detection of dozens of water vapour lines in the far-infrared and sub-millimetre spectrum of IRC +10216 using the Herschel satellite. This includes some high-excitation lines with energies corresponding to approximately 1,000 K, which can be explained only if water is present in the warm inner sooty region of the envelope. A plausible explanation for the warm water appears t...
Biophysical Journal
Accurate FRET Measurements within Single Diffusing Biomolecules Using Alternating-Laser Excitation2005 •
Nature Nanotechnology
Multimodal optical sensing and analyte specificity using single-walled carbon nanotubes2009 •
Physical Chemistry Chemical Physics
Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells2013 •
J. Mater. Chem. C
Polaron self-localization in white-light emitting hybrid perovskitesChemical Communications
Fluorescent or not? Size-dependent fluorescence switching for polymer-stabilized gold clusters in the 1.1–1.7 nm size range2008 •
Scientific reports
Hyperspectral Microscopy of Near-Infrared Fluorescence Enables 17-Chirality Carbon Nanotube Imaging2015 •
Journal of Photochemistry and Photobiology A: Chemistry
Lactim–lactam tautomerism is favoured over enol–keto tautomerism in 2-hydroxy-5-(4-fluorophenyl)nicotinic acid: Experimental and quantum chemical approach2010 •
Journal of Photochemistry and Photobiology A-chemistry
Study on intramolecular charge transfer fluorescence properties of trans-4-[4′-(N,N′-dimethylamino)styryl]pyridine: Effect of solvent and pH2011 •
Tetrahedron Letters
A fluorescent hydrogen peroxide probe based on a ‘click’ modified coumarin fluorophore2010 •
J Amer Soc Mass Spectrom
Electro nP h otodetachment Dissociation of DNA Anions with Covalentl yo r Noncovalently Bound Chromophores2007 •
Nature chemical biology
Mechanism of photoprotection in the cyanobacterial ancestor of plant antenna proteins2015 •
Chemistry & Biology
Understanding the Structure/Activity Relationships of the Iron Regulatory Peptide Hepcidin2011 •
2011 •
Nature Chemistry
Photoelectrochemical Complexes for Solar Energy Conversion That Chemically and Autonomously Regenerate2010 •
2010 •
The Journal of Chemical Physics
Doping with multiple cations and failure of charge transfer in large ionized helium dropletsScientific Reports
Intense bone fluorescence reveals hidden patterns in pumpkin toadletsJournal of Molecular Structure
Influence of chlorine substitution on intramolecular hydrogen bond energy and ESIPT barrier: Experimental and theoretical measurements on the photophysics of 3,5-dichlorosalicylic acid2010 •
Applied Physics Letters
Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas2013 •
Naturwissenschaften
Visualizing different uranium oxidation states during the surface alteration of uraninite and uranium tetrachloride2009 •
Proceedings of the Royal Society B: Biological Sciences
A shared chemical basis of avian host-parasite egg colour mimicry2012 •
2005 •
Nature communications
A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells2016 •
Proceedings of the Royal Society B
Red fluorescence increases with depth in reef fishes, supporting a visual function, not UV protection2014 •
International Journal of Molecular Sciences
Rise-Time of FRET-Acceptor Fluorescence Tracks Protein Folding2014 •
Nature Communications
Growth of carbon nanotubes via twisted graphene nanoribbons2013 •
Scientific Reports
Fluorescent silk cocoon creating fluorescent diatom using a “Water glass-fluorophore ferry”2013 •
Nature Communications
Binder driven self-assembly of metal-organic cubes towards functional hydrogelsJournal of Raman Spectroscopy
‘Green earths’: vibrational and elemental characterization of glauconites, celadonites and historical pigments2008 •
Journal of Photochemistry and Photobiology A-chemistry
Photo-spectroscopic properties of benzothiadiazole-containing pendant polymers for photovoltaic applications2011 •