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| Open AccessDirect observation of photoinduced sequential spin transition in a halogen-bonded hybrid system by complementary ultrafast optical and electron probes
Halogen bond is desired for tuning electronic properties by external stimuli. Here, authors reveal a sequential activation of spin crossover and dimer softening, unveiling a key transient state in a prototypical halogen-bonded material.
- Yifeng Jiang
- , Stuart Hayes
- & R. J. Dwayne Miller
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Article
| Open AccessEfficient intersystem crossing and tunable ultralong organic room-temperature phosphorescence via doping polyvinylpyrrolidone with polyaromatic hydrocarbons
Room temperature phosphorescent polymers have potential in a range of applications, but achieving the desired properties can be challenging. Here, the authors report the development of such polymer materials by doping with polyaromatic hydrocarbons.
- Guangxin Yang
- , Subin Hao
- & Li Dang
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Article
| Open AccessReal-time observation of two distinctive non-thermalized hot electron dynamics at MXene/molecule interfaces
Photoexcited MXenes could transfer charge carriers to or heat molecules at their interfaces. Here, the authors show using time-resolved spectroscopy that the non-thermalized carriers can directly transfer to molecules or heat them within 125 fs.
- Qi Zhang
- , Wei Li
- & Xueming Yang
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| Open AccessTracking nuclear motion in single-molecule magnets using femtosecond X-ray absorption spectroscopy
The authors use femtosecond K-edge X-ray absorption spectroscopy to follow nuclear motion in a manganese-based tri-nuclear single-molecule magnet, and resolve changes in bond lengths on the order of hundreds of ångströms and on sub-picosecond timescales.
- Kyle Barlow
- , Ryan Phelps
- & J. Olof Johansson
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Article
| Open AccessGiant magneto-photoluminescence at ultralow field in organic microcrystal arrays for on-chip optical magnetometer
The optical detection of magnetic fields is difficult for low field strengths. Here, the authors show how strong magneto-photoluminescence can be achieved in rubrene microcrystals and demonstrate its application in a magnetometer.
- Hong Wang
- , Baipeng Yin
- & Chuang Zhang
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Article
| Open AccessEffect of crystal facets in plasmonic catalysis
Crystal facets are known to be important in traditional heterogeneous catalysis, yet this effect has not been studied in plasmon-assisted catalysis. Here, the authors investigate the impact facets have on CO2 reduction using plasmonic Au NPs.
- Yicui Kang
- , Simão M. João
- & Emiliano Cortés
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Article
| Open AccessOptically induced charge-transfer in donor-acceptor-substituted p- and m- C2B10H12 carboranes
Icosahedral carboranes have long been considered to be aromatic but the extent of conjugation between these clusters and their substituents is still being debated. Here the authors demonstrate carboranes as conjugated bridges in optical functional chromophores.
- Lin Wu
- , Marco Holzapfel
- & Lei Ji
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Article
| Open AccessEmissive brightening in molecular graphene nanoribbons by twilight states
The authors demonstrate that the band structure of graphene nanoribbons is modulated by cove edges, brightening the luminescence 4-fold via emission from otherwise dark twilight states. High spectral resolution of the optical response reveals strong vibron-electron coupling
- Bernd K. Sturdza
- , Fanmiao Kong
- & Robin J. Nicholas
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| Open AccessRetinal photoisomerization versus counterion protonation in light and dark-adapted bacteriorhodopsin and its primary photoproduct
Malakar et al. investigate the photochemical dynamics in the isomerization of bacteriorhodopsin light and dark-adapted forms and in the first photocycle intermediate, K. The results prompt a reevaluation of the counter ion model, revealing that a different protonation then that shown in the classic quadrupole so far considered must be employed to account for the experimental data.
- Partha Malakar
- , Samira Gholami
- & Sanford Ruhman
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Article
| Open AccessDisentangling the multiorbital contributions of excitons by photoemission exciton tomography
Understanding excitonic optical excitations is integral to improving optoelectronic and photovoltaic semiconductor devices. Here, Bennecke et al. use photoemission exciton tomography to unravel the multiorbital electron and hole contributions of entangled excitonic states in the prototypical organic semiconductor C60.
- Wiebke Bennecke
- , Andreas Windischbacher
- & Stefan Mathias
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Article
| Open AccessAg3PO4 enables the generation of long-lived radical cations for visible light-driven [2 + 2] and [4 + 2] pericyclic reactions
Photoredox catalysis is an important approach for synthesizing fine chemicals from olefins, but the limited lifetime of radical cation intermediates severely restricts the efficiency. Here, the authors report that Ag3PO4 can efficiently catalyze intramolecular and intermolecular [2 + 2] and Diels–Alder cycloadditions under visible-light irradiation.
- Lirong Guo
- , Rongchen Chu
- & Yifeng Wang
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Article
| Open AccessAnisotropic carrier dynamics and laser-fabricated luminescent patterns on oriented single-crystal perovskite wafers
Based on differently-oriented MAPbBr3 single-crystal wafers, the authors revealed anisotropic carrier dynamics by using angle-resolved pump-probe technique, and the microstructural mechanism of the femtosecond laser-induced emission enhancement
- Chao Ge
- , Yachao Li
- & Yang Liu
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Article
| Open AccessRydberg electron stabilizes the charge localized state of the diamine cation
Previous theoretical interpretations of the Rydberg spectra of dimethylpiperazine (DMP) debated the existence of a localized minimum on the surface of the DMP+ cation. Here, the authors show a substantial influence of the Rydberg electron on the molecular structure, restoring the localized minimum.
- Marc Reimann
- , Christoph Kirsch
- & Martin Kaupp
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Article
| Open AccessPromoting multiexciton interactions in singlet fission and triplet fusion upconversion dendrimers
The impact of multiexcitonic through-space interactions in macromolecular architectures is poorly investigated. Here the authors use dendritic macromolecules to study the effect of interchromophore interactions on the dynamics of multiexciton generation and decay as a function of dendrimer generation.
- Guiying He
- , Emily M. Churchill
- & Luis M. Campos
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Article
| Open AccessDirectly imaging excited state-resolved transient structures of water induced by valence and inner-shell ionisation
Capturing the detailed structural evolution of electronic excited states is a challenging but critical step to understand and control ultrafast molecular dynamics. Here, combining a Coulomb explosion imaging approach and molecular dynamics simulations, the authors retrieve the transient geometry of the ground and excited states of D2O mono- and dication with few femtosecond, few picometre accuracy.
- Zhenzhen Wang
- , Xiaoqing Hu
- & Dajun Ding
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Article
| Open AccessRoom temperature valley polarization via spin selective charge transfer
Valleytronics is a portmanteau of ‘valley’ and ‘electronics’ and refers to the use of the valley degree of freedom, present in some materials, for encoding and processing information. Here, Shrestha et al demonstrate a room temperature valley polarization in heterostructures composed of molybdenum disulfide and a chiral lead halide perovskite, an important step in development of valleytronics.
- Shreetu Shrestha
- , Mingxing Li
- & Mircea Cotlet
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Article
| Open AccessMinimizing non-radiative decay in molecular aggregates through control of excitonic coupling
Exciton delocalization in molecular aggregates is suggested to counteract the Energy Gap Law. Here, authors reveal the underlying physical picture and find the optimal excitonic coupling that minimizes nonradiative decay by nearly exact simulations.
- Yuanheng Wang
- , Jiajun Ren
- & Zhigang Shuai
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Article
| Open AccessTheory predicts UV/vis-to-IR photonic down conversion mediated by excited state vibrational polaritons
Vibrational polaritons steer chemical reactions and control quantum states for information processing. Here the authors predict their formation during electronic photo-excitation, enabling a down-conversion of visible to infrared photons.
- Connor K. Terry Weatherly
- , Justin Provazza
- & Roel Tempelaar
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Article
| Open AccessMesitylated trityl radicals, a platform for doublet emission: symmetry breaking, charge-transfer states and conjugated polymers
Neutral π-radicals are potential emitters for optoelectronic devices due to the absence of energetically low-lying non-emissive states. Here, the authors report mesityl-substituted tris(2,4,6-trichlorophenyl)methyl radicals and achieve maximum device efficiency of 28% at a wavelength of 689 nm.
- Petri Murto
- , Rituparno Chowdhury
- & Hugo Bronstein
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Article
| Open AccessLongevity gene responsible for robust blue organic materials employing thermally activated delayed fluorescence
High throughput virtual screening of robust blue thermally activated delayed fluorescent emitters has yet been implemented. Here, authors reveal a linear relationship of the difference between bond dissociate energy and first triplet state energy with the logarithm of device operational lifetime.
- Qing-Yu Meng
- , Rui Wang
- & Juan Qiao
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Article
| Open AccessRegulating the proximity effect of heterocycle-containing AIEgens
Proximity effect (PE) can impact the behaviour of heterocyclic luminogens, but is rarely used to manipulate the aggregation-induced emission (AIE) related properties. Here, the authors systematically illustrate the impacts of PE and AIE on luminescent behaviors.
- Jianyu Zhang
- , Yujie Tu
- & Ben Zhong Tang
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Article
| Open AccessRevealing core-valence interactions in solution with femtosecond X-ray pump X-ray probe spectroscopy
Pump-probe spectroscopy is routinely used to interrogate ultrafast valence electronic and vibrational dynamics in complex systems. Here, the authors extend this technique to the X-ray regime using a sequence of femtosecond X-ray pulses to understand core-valence interactions in a solvated molecular complex.
- Robert B. Weakly
- , Chelsea E. Liekhus-Schmaltz
- & Munira Khalil
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Article
| Open AccessIn-plane and out-of-plane excitonic coupling in 2D molecular crystals
The mixing between Frenkel and charge-transfer characters in molecular excitons is difficult to analyze. Here, the authors demonstrate the onset and evolution of the mixing using 2D perylene molecular crystals by measuring the reorientation of emission transition dipoles with varying thicknesses.
- Dogyeong Kim
- , Sol Lee
- & Sunmin Ryu
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Article
| Open AccessMany-body screening effects in liquid water
Electron screening is crucial to interpret inelastic X-ray scattering experiments in materials. Here the authors use a combined analysis based on the Bethe-Salpeter equation and time-dependent density functional theory to calculate the dielectric function and obtain the band gap of liquid water.
- Igor Reshetnyak
- , Arnaud Lorin
- & Alfredo Pasquarello
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Article
| Open AccessFerricyanide photo-aquation pathway revealed by combined femtosecond Kβ main line and valence-to-core x-ray emission spectroscopy
Reliably identifying transient intermediates is crucial to elucidate chemical reaction mechanisms. Here, the authors use femtosecond Fe Kβ main line and valence-to-core x-ray emission spectroscopy to characterize a short-lived intermediate of the aqueous ferricyanide photo-aquation reaction.
- Marco Reinhard
- , Alessandro Gallo
- & Dimosthenis Sokaras
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Article
| Open AccessConfining donor conformation distributions for efficient thermally activated delayed fluorescence with fast spin-flipping
The distribution of dihedral angles in film state has significant influence on excited state lifetimes of thermally activated delayed fluorescence emitters. Here authors report conformation distribution confinement strategy to achieve fast spin-flipping for efficient organic light-emitting diodes.
- Weidong Qiu
- , Denghui Liu
- & Shi-Jian Su
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Article
| Open AccessAnomalous deep-red luminescence of perylene black analogues with strong π-π interactions
Perylene bisimide dyes are high-performance pigments that have red, maroon or black colors, but with typically only weak fluorescence in the solid state. Here, the authors report a series of π-stacked PBI derivatives that show highly efficient deep-red fluorescence in the solid state.
- Ningning Tang
- , Jiadong Zhou
- & Zengqi Xie
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Article
| Open AccessSinglet fission as a polarized spin generator for dynamic nuclear polarization
Singlet fission (SF) can create spin-polarized quintet states in organic systems, but this effect and its potential applications have not been sufficiently explored. Here, authors demonstrate that SF in supramolecular assemblies of pentacene chromophores improves the sensitivity of magnetic resonance of water molecules through dynamic nuclear polarization in a water-glycerol glass.
- Yusuke Kawashima
- , Tomoyuki Hamachi
- & Nobuhiro Yanai
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| Open AccessElectronic excited states in deep variational Monte Carlo
Deep neural networks can learn and represent nearly exact electronic ground states. Here, the authors advance this approach to excited states, achieving high accuracy across a range of atoms and molecules, opening up the possibility to model many excited-state processes.
- M. T. Entwistle
- , Z. Schätzle
- & F. Noé
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| Open AccessEnergy cascades in donor-acceptor exciton-polaritons observed by ultrafast two-dimensional white-light spectroscopy
Exciton-polaritons are hybridized light-matter states that exhibit intriguing phenomena that are unobserved in purely excitonic states. Here, the authors elucidate the photophysical mechanism of polariton-assisted long-range energy transfer in carbon nanotubes using two-dimensional white-light spectroscopy and quantum calculations.
- Minjung Son
- , Zachary T. Armstrong
- & Martin T. Zanni
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Article
| Open AccessMachine learning the Hohenberg-Kohn map for molecular excited states
Density functional theory provides a formal map from the electron density to all observables of interest of a many-body system; however, maps for electronic excited states are unknown. Here, the authors demonstrate a data-driven machine learning approach for constructing multistate functionals.
- Yuanming Bai
- , Leslie Vogt-Maranto
- & William J. Glover
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Article
| Open AccessRetinal chromophore charge delocalization and confinement explain the extreme photophysics of Neorhodopsin
Fluorescent proteins that self-assemble and localize in the neuron membrane are vital in neurosciences, particularly in optogenetics applications. Here the authors present a quantum-mechanics/molecular mechanics model for the photoisomerization of the natural highly fluorescent Neorhodopsin, explaining the highly fluorescent quantum yield that could lead to effective visualization of neural signals.
- Riccardo Palombo
- , Leonardo Barneschi
- & Massimo Olivucci
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| Open AccessTowards the engineering of a photon-only two-stroke rotary molecular motor
Improving the efficiency of light-driven molecular rotary motors is a challenging task. Here, the authors combine theoretical modeling, synthesis and spectroscopy to prepare a prototype molecular motor capable of avoiding inefficient thermally activated motion; thus offering prospects to implement a 2-stroke photon-only molecular motor.
- Michael Filatov(Gulak)
- , Marco Paolino
- & Massimo Olivucci
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Article
| Open AccessOn the fluorescence enhancement of arch neuronal optogenetic reporters
Arch-3 rhodopsin variants are common fluorescent reporters of neuronal activity. Here, the authors show with quantum chemical modelling that a set of these proteins reveals a direct proportionality between their observed fluorescence intensity and the stability of an exotic excited-state diradical intermediate.
- Leonardo Barneschi
- , Emanuele Marsili
- & Massimo Olivucci
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Article
| Open AccessTriple ionization and fragmentation of benzene trimers following ultrafast intermolecular Coulombic decay
Higher-order aromatic clusters are prevalent in biochemical systems, but a full understanding of their structural and dynamical properties is lacking. Here, the authors demonstrate that inner-valence ionization can induce ultrafast relaxation and further fragmentation mechanisms in benzene trimers.
- Jiaqi Zhou
- , Xitao Yu
- & Xueguang Ren
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Article
| Open AccessSub-10-fs observation of bound exciton formation in organic optoelectronic devices
Ultrafast action spectroscopies of organic optoelectronic devices reveal that the formation of bound exciton state occurs as fast as 10 fs. Excitons having excess energy can dissociate spontaneously within 50-fs before acquiring bound character.
- Marios Maimaris
- , Allan J. Pettipher
- & Artem A. Bakulin
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| Open AccessSteering the multiexciton generation in slip-stacked perylene dye array via exciton coupling
Understanding structure-property relationship of dye arrays is of great importance for designing organic photonic and photovoltaic materials. Here, authors present a slip-stacked perylene bisimide array as a model system to investigate singlet fission mechanisms by depending upon interchromophoric interaction.
- Yongseok Hong
- , Maximilian Rudolf
- & Frank Würthner
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Article
| Open AccessPhotochemical spin-state control of binding configuration for tailoring organic color center emission in carbon nanotubes
Chemical functionalization of the sidewalls of single-wall carbon nanotubes (SWCNTs) is an emerging route to introduce fluorescent quantum defects and tailor the emission properties. Here, authors demonstrate that spin-selective photochemistry diversifies SWCNT emission tunability by controlling the morphology of the emitting sites.
- Yu Zheng
- , Yulun Han
- & Sergei Tretiak
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Article
| Open AccessSecondary through-space interactions facilitated single-molecule white-light emission from clusteroluminogens
Although mature and systematic theories of molecular photophysics have been developed, it is still challenging to endow clusteroluminogens (CLgens) with designed photophysical properties by manipulating through-space interactions. Here, the authors design three CLgens that show multiple emissions and white-light emission in the crystalline state, and emphasize the important role of secondary through-space interactions between the acceptor and non-conjugated donor units.
- Jianyu Zhang
- , Parvej Alam
- & Ben Zhong Tang
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Article
| Open AccessGeneration and direct observation of a triplet arylnitrenium ion
Nitrenium ions are highly electrophilic reactive intermediates of formula R−N−R+, nitrogen analogue of carbenes. Here the authors report the detection of a triplet nitrenium ion using time-resolved spectroscopic methods and ab initio computations, allowing a glimpse at the properties and behavior of this important class of intermediates.
- Lili Du
- , Juanjuan Wang
- & Arthur H. Winter
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Article
| Open AccessExcited state non-adiabatic dynamics of large photoswitchable molecules using a chemically transferable machine learning potential
The authors introduce a diabatic neural network to accelerate excitedstate, non-adiabatic simulations of azobenzene derivatives. The model predicts quantum yields for unseen species that are correlated with experiment.
- Simon Axelrod
- , Eugene Shakhnovich
- & Rafael Gómez-Bombarelli
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Article
| Open AccessDirect observation of ultrafast exciton localization in an organic semiconductor with soft X-ray transient absorption spectroscopy
A detailed understanding of ultrafast exciton dynamics is crucial for improving the efficiency of organic light-harvesting-devices. Here, the authors track exciton localization on a sub-50 fs timescale in an organic semiconductor using time resolved soft x-ray absorption spectroscopy.
- D. Garratt
- , L. Misiekis
- & J. P. Marangos
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Article
| Open AccessFree charge photogeneration in a single component high photovoltaic efficiency organic semiconductor
When light hits organic semiconductors, bound charge pairs, called excitons, are usually produced. Here, the authors show that in the best performing organic solar material to date, free charges, rather than excitons, are directly created by light.
- Michael B. Price
- , Paul A. Hume
- & Justin M. Hodgkiss
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Article
| Open AccessTriplet-driven chemical reactivity of β-carotene and its biological implications
The endoperoxides of β-carotene play a key role in signaling of photooxidative stress in plant cells and are regarded as the products of chemical deactivation of singlet oxygen. The authors show that these compounds are instead formed in a reaction between oxygen and β-carotene in their triplet states, revealing the importance of the triplet states in the photoprotection of photosynthetic apparatus.
- Mateusz Zbyradowski
- , Mariusz Duda
- & Leszek Fiedor
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| Open AccessChiral photochemistry of achiral molecules
The authors report non-adiabatic first principles molecular dynamics to show how an achiral molecule can be converted to a chiral one upon photoexcitation. These results demonstrate the possibility of asymmetric photochemistry starting from achiral reactants.
- Umberto Raucci
- , Hayley Weir
- & Todd J. Martínez
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Article
| Open AccessDoubly linked chiral phenanthrene oligomers for homogeneously π-extended helicenes with large effective conjugation length
Helically twisted conductive nanocarbon materials are applicable to optoelectronic and electromagnetic molecular devices but the design of nanocarbons with an absorption edge in the low energy region is challenging. Here, the authors report the synthesis of a helically fused oligophenanthrenes and demonstrate an increased effective conjugation length leading to an absorption edge in the NIR region.
- Yusuke Nakakuki
- , Takashi Hirose
- & Kenji Matsuda
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Article
| Open AccessPhotochemistry of the pyruvate anion produces CO2, CO, CH3–, CH3, and a low energy electron
Pyruvic acid and its conjugate base, the pyruvate anion, are largely present in the atmosphere. Here the authors, using photoelectron imaging and quantum chemistry calculations, investigate the photochemistry of isolated pyruvate anions initiated by UVA radiation and report the formation of CO2, CO, and CH3− further decomposing into CH3 and a free electron.
- Connor J. Clarke
- , Jemma A. Gibbard
- & Basile F. E. Curchod
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Article
| Open AccessUnconventional excited-state dynamics in the concerted benzyl (C7H7) radical self-reaction to anthracene (C14H10)
The reaction of benzyl radical self-reaction to anthracene opens-up a previously overlooked avenue for a more efficient synthesis of aromatic, multi-ringed structures via excited state dynamics in the gas phase.
- Ralf. I. Kaiser
- , Long Zhao
- & Alexander M. Mebel
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Article
| Open AccessInternal Stark effect of single-molecule fluorescence
The internal Stark effect, a shift of the spectral lines of a chromophore induced by electrostatic fields in its close environment, plays an important role in nature. Here the authors observe a Stark shift in the fluorescence spectrum of a phthalocyanine molecule upon charge modifications within the molecule itself, achieved by sequential removal of the central protons with a STM tip.
- Kirill Vasilev
- , Benjamin Doppagne
- & Guillaume Schull