A5057480896- Advanced Chemical Physics Studies
- Mass Spectrometry Techniques and Applications
- Photoreceptor and optogenetics research
- Atomic and Molecular Physics
- Photochemistry and Electron Transfer Studies
- Astrophysics and Star Formation Studies
- Spectroscopy and Quantum Chemical Studies
- Advanced Fluorescence Microscopy Techniques
- Photosynthetic Processes and Mechanisms
- Photochromic and Fluorescence Chemistry
- Atmospheric Ozone and Climate
- Analytical Chemistry and Chromatography
- bioluminescence and chemiluminescence research
- Molecular Sensors and Ion Detection
- Porphyrin and Phthalocyanine Chemistry
- Synthesis and Properties of Aromatic Compounds
- Luminescence and Fluorescent Materials
- Molecular Spectroscopy and Structure
- Fullerene Chemistry and Applications
- Radical Photochemical Reactions
- Advanced NMR Techniques and Applications
- Inorganic Fluorides and Related Compounds
- Electrochemical Analysis and Applications
- Crystallography and Radiation Phenomena
- Ion-surface interactions and analysis
University of East Anglia
2019-2025
Norwich Research Park
2019-2024
The University of Melbourne
2016-2021
Durham University
2014-2019
University of Oxford
2011-2015
Durham Technical Community College
2015
Oxfam
2014
University of Canterbury
2008-2012
Abstract After decades of searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance cyanonaphthalene (CNN, C 10 H 7 CN) Taurus Molecular Cloud (TMC-1) is six orders magnitude higher than expected from astrophysical modeling. Here, we report unimolecular dissociation and radiative cooling rate coefficients 1-CNN isomer its cationic form. These results are based on measurements time-dependent neutral product...
Abstract This roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics molecules clusters gas phase. It comprises nineteen contributions by scientists with leading expertise complementary experimental theoretical techniques to probe on timescales spanning twenty order magnitudes, from attoseconds minutes beyond, for systems ranging complexity smallest (diatomic) nanoparticles. Combining some these opens up new avenues unravel hitherto unexplored...
The recently developed method of frequency-, angle-, and time-resolved photoelectron imaging (FAT-PI) applied to the study dynamics resonances open-shell anions is reviewed. basic principles its experimental realisation are outlined. a number radical quinone then considered. Firstly, we show for para-benzoquinone how frequency- angle-resolved provides finger-prints yields deep mechanistic insight into relaxation resonances. effect chemical substitutions para-quinone electrophore on...
The resonant attachment of a free electron to closed shell neutral molecule and the interplay between following detachment electronic relaxation channels represents fundamental but common process throughout chemical biochemical systems. new methodology anion frequency-resolved photoelectron imaging is detailed used map out molecular excited state dynamics gas-phase para-benzoquinone, which accepting moiety in many biological electron-transfer chains. Three-dimensional spectra excitation...
Donor-acceptor Stenhouse adducts (DASAs) are a new class of photoswitching molecules with excellent fatigue resistance and synthetic tunability. Here, tandem ion mobility mass spectrometry coupled laser excitation is used to characterize the photocyclization reaction isolated, charge-tagged DASA over 450-580 nm range. The experimental maximum response at 530 agrees multireference perturbation theory calculations for S1 ← S0 transition 533 nm. Photocyclization in gas phase involves absorption...
A combined frequency-, angle-, and time-resolved photoelectron spectroscopy study is used to unravel the excited state dynamics following UV excitation of isolated anionic chromophore green fluorescent protein (GFP). The optically bright S3 state, which populated for hv > 3.7 eV, shown decay predominantly by internal conversion S2 that in turn autodetaches neutral ground state. For 4.1 a new favorable autodetachment channel from becomes available, leads formation an results indicate GFP...
Isolated π-stacked dimer radical anions present the simplest model of an excess electron in a environment. Here, frequency-, angle-, and time-resolved photoelectron imaging together with electronic structure calculations have been used to characterise coenzyme Q0 anion its exited state dynamics. In ground state, is localised on one monomer planar para-quinone ring, which solvated by second carbonyl groups are bent out ring plane. Through π-stacking interaction, exhibits number...
Non-valence states in neutral molecules (Rydberg states) have well-established roles and importance photochemistry, however, considerably less is known about the role of non-valence photo-induced processes anions. Here, femtosecond time-resolved photoelectron imaging used to show that photoexcitation S1(ππ*) state methyl ester deprotonated para-coumaric acid - a model chromophore for photoactive yellow protein (PYP) leads bifurcation excited wavepacket. One part remains on forming twisted...
The experimental determination of absolute total electron impact ionization cross-sections for polyatomic molecules has traditionally been a difficult task and restricted to small range species. This article reviews the performance three models estimate maximum some 65 organic halocarbon Cross-sections all species studied have measured experimentally using same instrument, providing complete data set comparison with model predictions. are empirical correlation between cross-section molecular...
Frequency-, angle-, and time-resolved photoelectron imaging of gas-phase menadione (vitamin K<sub>3</sub>) radical anions is used to show that quasi-bound resonances the anion can act as efficient doorway states produce metastable ground electronic state on a sub-picosecond timescale.
Nonvalence states of molecular anions play key roles in processes, such as electron mobility, rare-gas liquids, radiation-induced damage to DNA, and the formation interstellar medium. Recently, a class nonvalence bound anion state has been predicted by theory which correlation forces are predominantly responsible for binding excess electron. We present direct spectroscopic observation this correlation-bound (CBS) para-toluquinone trimer cluster anion. Time-resolved photoelectron velocity map...
Absolute gas-phase electron ionization cross-sections have been measured for functional group analogues of the nucleobase and sugar backbone constituents DNA RNA.
Carbon aggregates containing between 10 and 30 atoms preferentially arrange themselves as planar rings. To learn more about this exotic allotrope of carbon, electronic spectra are measured for even cyclo[n]carbon radical cations (C14+-C36+) using two-color photodissociation action spectroscopy. eliminate spectral contributions from other isomers, the target isomer-selected a drift tube ion mobility spectrometer prior to spectroscopic interrogation. The exhibit sharp transitions spanning...
Naphthalene and azulene are isomeric polycyclic aromatic hydrocarbons (PAHs) topical in the context of astrochemistry due to recent discovery substituted naphthalenes Taurus Molecular Cloud-1 (TMC-1). Here, thermal- photo-induced isomerization, dissociation, radiative cooling dynamics energized (vibrationally hot) naphthalene (Np+) (Az+) radical cations, occurring over microsecond seconds timescale, investigated using a cryogenic electrostatic ion storage ring, affording “molecular cloud...
Separation and structural identification of lipids remain a major challenge for contemporary lipidomics. Regioisomeric differing only in position(s) unsaturation are often not differentiated by conventional liquid chromatography-mass spectrometry approaches leading to the incomplete, or sometimes incorrect, assignation molecular structure. Here we describe an investigation gas phase separations differential-mobility (DMS) series synthetic analogues recently described 1-deoxysphingosine. The...
Fluorescent proteins have revolutionized the visualization of biological processes, prompting efforts to understand and control their intrinsic photophysics. Here we investigate photoisomerization deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI-), chromophore in green fluorescent protein Dronpa protein, where it plays a role switching between nonfluorescent states. In present work, isolated HBDI- molecules are switched Z E forms gas phase tandem ion mobility mass...
The utility of tandem ion mobility mass spectrometry coupled with electronic spectroscopy to investigate protomer-specific photochemistry is demonstrated by measuring the photoisomerization response for protomers protonated 4-dicyanomethylene-2-methyl-6-para-dimethylaminostyryl-4H-pyran (DCM) molecules. target DCMH+ species has three that are distinguished their different collision cross sections He, N2, and CO2 buffer gases, trends in abundance source conditions, from responses. trans-DCMH+...
Frequency-resolved (2D) photoelectron (PE) spectra of the anionic clusters (C6F6) n-, for n = 1-5, and time-resolved PE I-C6F6 are presented using a newly built instrument supported by electronic structure calculations. From 2D spectra, vertical detachment energy (VDE) C6F6- was measured to be 1.60 ± 0.01 eV, adiabatic (ADE) ≤0.70 eV. The also contain fingerprints resonance dynamics over certain photon ranges, in agreement with An action spectrum lowest is presented. n- show that cluster can...
Nonvalence states of neutral molecules (Rydberg states) play important roles in nonadiabatic dynamics excited states. In anions, such transitions between nonvalence and valence have been much less explored even though they are believed to electron capture state anions. The aim this Feature Article is provide an overview recent experimental observations, based on time-resolved photoelectron imaging, anions demonstrate that may be commonplace the molecular cluster
Several small Polycyclic Aromatic Hydrocarbons (PAHs) have been identified recently in the Taurus Molecular Cloud (TMC-1) using radio telescope observations. Reproducing observed abundances of these molecules has a challenge for astrochemical models. Rapid radiative cooling PAHs by Recurrent Fluorescence (RF), emission optical photons from thermally populated electronically excited states, shown to efficiently stabilize following ionization, augmenting their resilience astronomical...
Infrared (IR) cooling of polycyclic aromatic hydrocarbon (PAH) molecules is a major radiative stabilization mechanism PAHs present in space and the origin infrared bands (AIBs). Here, we report an anharmonic cascade model master equation framework to IR emission rates spectra energized as function internal energy. The underlying (simple harmonic cascade) for fundamental vibrations has been developed through modeling PAH cations other carboneaous ions measured electrostatic ion storage ring...
Betaine-30, is well established as a standard dye for solvatochromism, and has long been studied by ultrafast spectroscopy. Electronic excitation leads to rapid intramolecular electron transfer, while the decay of resulting state corresponds back transfer electronic ground state. Thus, Betaine-30’s photophysics offer route probing role vibrational solvent dynamics play in reaction rates. Here we probe excited Betaine-30 two solvents (ethanol acetonitrile) means two-dimensional Population...
Indene (C$_9$H$_8$) is the only polycyclic pure hydrocarbon identified in interstellar medium to date, with an observed abundance orders of magnitude higher than predicted by astrochemical models. The dissociation and radiative stabilization vibrationally-hot indene cations investigated measuring time-dependent neutral particle emission rate from ions a cryogenic ion-beam storage ring for up 100~ms. Time-resolved measurements kinetic energy released upon hydrogen atom loss C$_9$H$_8^+$,...
Incorporation of fluorescent proteins (FPs) into biological systems has revolutionised bioimaging and the understanding cellular processes. Ongoing developments FPs are driving efforts to characterise fundamental photoactive unit...