A5055092602- Advanced Chemical Physics Studies
- Laser-Matter Interactions and Applications
- Molecular Spectroscopy and Structure
- Advanced X-ray Imaging Techniques
- Atomic and Molecular Physics
- Astrophysics and Star Formation Studies
- Atmospheric Ozone and Climate
- Astro and Planetary Science
- Laser-Plasma Interactions and Diagnostics
- Mass Spectrometry Techniques and Applications
- Free Radicals and Antioxidants
- Chemical Thermodynamics and Molecular Structure
- Advanced Electron Microscopy Techniques and Applications
- Nuclear Physics and Applications
- Electron and X-Ray Spectroscopy Techniques
- Laser-induced spectroscopy and plasma
- Atmospheric chemistry and aerosols
- Laser Design and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Chemical Reactions and Mechanisms
- Spectroscopy and Laser Applications
- Inorganic Fluorides and Related Compounds
- Quantum, superfluid, helium dynamics
- Particle Accelerators and Free-Electron Lasers
- Advanced Physical and Chemical Molecular Interactions
University of Liverpool
2023-2024
University of Trento
2020-2024
Dublin City University
2008-2024
University of Oxford
2019
Oxfam
2019
Two-color, single-shot time-of-flight electron spectroscopy of atomic neon was employed at the Linac Coherent Light Source (LCLS) to measure laser-assisted Auger decay in x-ray regime. This x-ray-optical cross-correlation technique provides a straightforward, non-invasive and on-line means determining duration femtosecond (>40 fs) pulses. In combination with theoretical model process based on soft-photon approximation, we were able obtain LCLS pulse extract mean value temporal jitter between...
Two-color multiphoton ionization of atomic helium was investigated by combining extreme ultraviolet (XUV) radiation from the Free Electron Laser in Hamburg with an intense synchronized optical laser. In photoelectron spectrum, lines associated direct and above-threshold show strong variations their amplitudes as a function both intensity dressing field relative orientation linear polarization vectors two fields. The dependence provides insight into symmetry outgoing electrons ionization....
Using a noninvasive, electro-optically based electron bunch arrival time measurement at FLASH (free laser in Hamburg) the temporal resolution of two-color pump-probe experiments has been significantly improved. The system determines relative extended ultraviolet pulse and an amplified Ti:sapphire femtosecond-laser interaction region better than 90 fs rms. In benchmarking experiment using above threshold ionization noble gases, enhancement timing by factor 4 compared to uncorrected data is obtained.
We present a systematic study of the photoionization noble gas atoms exposed simultaneously to ultrashort (20 fs) monochromatic (1–2% spectral width) extreme ultraviolet (XUV) radiation from Free-electron Laser in Hamburg (FLASH) and intense synchronized near-infrared (NIR) laser pulses with intensities up about 1013 W cm−2. Already at modest NIR dressing field, XUV-induced lines are split into sequence peaks due emission or absorption several additional infrared photons. observed...
Two-photon excitation of a single-photon forbidden Auger resonance has been observed and investigated using the intense extreme ultraviolet radiation from free electron laser in Hamburg. At wavelength 26.9 nm (46 eV) two photons promoted $3d$ core to outer $4d$ shell. The subsequent decay, as well several nonlinear above threshold ionization processes, were studied by spectroscopy. experimental data are excellent agreement with theoretical predictions analysis underlying multiphoton processes.
We have observed the simultaneous inner-shell absorption of two extreme-ultraviolet photons by a Xe atom in an experiment performed at short-wavelength free electron laser facility FLASH. Photoelectron spectroscopy permitted us to unambiguously identify feature resulting from ionization single $4d$ subshell each energy $(93\ifmmode\pm\else\textpm\fi{}1)\text{ }\text{ }\mathrm{eV}$. The feature's intensity has quadratic dependence on pulse energy. results are discussed and interpreted within...
Coulomb crystals have proven to be powerful and versatile tools for the study of ion–molecule reactions under cold controlled conditions. Reactions in are typically monitored through a combination situ fluorescence imaging laser-cooled ions destructive time-of-flight mass spectrometry measurements ejected ions. However, neither these techniques is able provide direct structural information on positions nonfluorescing "dark" within crystal. In this work, obtained using phosphor screen...
Combined experimental and computational study of the astrochemically relevant reaction HCNH 2 ˙ + H CNH˙ radical cations with propene (C 3 6 ).
Methanol is a key species in astrochemistry as its presence and reactivity provides primary route to the synthesis of more complex interstellar organic molecules (iCOMs) that may eventually be incorporated newly formed planetary systems. In medium, methanol by hydrogenation CO ices on grains, fate upon collisions with ions should accounted for correctly model iCOM abundances objects at various stages stellar evolution. The absolute cross sections (CSs) branching ratios (BRs) He˙+ CH3OH are...
In this work we report on the ionization of a gaseous neon target by combining extreme ultraviolet (XUV) radiation from Free Electron Laser in Hamburg with an intense synchronized optical laser. Applying energy-resolved photoelectron spectroscopy, dependence electrons ejected singly charged (Ne+) relative polarization XUV and laser fields was investigated. The electron spectra exhibit strong degree orientation linear vectors. A quantitative analysis undertaken using multichannel...
We present a comprehensive experimental study into the dissociative electron ionization dynamics of CF3I at energies ranging from 20 to 100 eV. A beam-gas instrument has been used measure absolute total cross-section for molecule over energy range 0 300 Coupled with data an electron-molecule crossed beam velocity-map imaging instrument, this allows partial cross-sections be determined formation each ionic fragment. These reveal number fragmentation channels involving both C-I and C-F bond...
In this paper, we report results on two-colour above-threshold ionisation, where extreme ultraviolet pulses of femtosecond duration were synchronised to intense infrared laser picosecond duration, in order study the laser-assisted photoelectric effect atomic helium, neon, krypton and xenon which leads appearance characteristic sidebands photoelectron spectra. The observed trends are found be well described by a simple model based soft-photon approximation, at least for relatively low optical...
Experimental and theoretical studies are presented on the reactivity of radical cation isomers H 2 CNH +• (methanimine) HCNH (aminomethylene) with ethyne (C ). Selective isomer generation is performed via dissociative photoionization suitable neutral precursors as well direct methanimine. Reactive cross sections (in absolute scales) product branching ratios measured a function photon collision energies. Differences between isomers’ discussed in light ab-initio calculations reaction...
Methanol is one of the most abundant interstellar Complex Organic Molecules (iCOMs) and represents a major building block for synthesis increasingly complex oxygen-containing molecules. The reaction between protonated methanol its neutral counterpart, giving dimethyl ether, (CH3)2OH+, along with ejection water molecule, has been proposed as key in ether space.Here, gas phase vibrational spectra (CH3)2OH+ product [C2H9O2]+ intermediate complex(es), formed under different pressure temperature...
The gas-phase reaction between the ethyl cation (C
Abstract New information demonstrating the importance of both sequential and simultaneous (or direct) multiphoton ionization inner shell electrons from neon is discussed in this paper. Ne was irradiated with intense 93 eV free electron laser (FEL) pulses at FLASH studied aid photoelectron spectrometry. This resulted two three photon, single double neon, removing 2s 2p subshells neutral atom multiple different pathways. The spectral features photoelectrons were identified through comparison...
Methyl cyanide (a.k.a. acetonitrile) is a molecule of great astrochemical interest as it one the simplest interstellar complex organic molecules (iCOMs) routinely detected in young solar analogues. It has been observed Class 0 and I hot-corinos (e.g. Taquet et al. 2015, Yang 2021, Bianchi 2022, Ceccarelli 2024), shocked regions (e.g., Codella 2009), well planet-forming disks (Öberg Bergner 2018, Loomis 2020, Ilee 2021). Moreover, CH3CN comets, including towards 67/P...
Methyl cyanide is one of the simplest interstellar complex organic molecules, widely detected in young solar analogues, shocked regions, protoplanetary disks and comets. CH3CN can be considered a key species to explore chemical connections between planet forming For such comparison meaningful kinetics data for reactions leading formation destruction must updated. We focus on methyl through collisions with He+. A combined experimental theoretical methodology employed obtain cross sections...
Context . CH 3 CN (methyl cyanide) is one of the simplest and most abundant interstellar complex organic molecules (iCOMs), has been detected in young solar analogues, shocked regions, protoplanetary discs, comets. can therefore be considered a key species to explore chemical connections between planet-forming disk phase However, for such comparison meaningful, kinetics data reactions leading formation destruction must updated. Aims Here we focus on methyl cyanide through collisions with He...
Interest in the observation and characterization of organic isomers astronomical environments has grown rapidly with an increase sensitivity detection techniques. Accurate modeling interpretation these require experimental isomer-specific reactivity spectroscopic measurements. Given abundance formaldehyde (H