James Cryan
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View article: Attosecond X-Ray Core-Level Chronoscopy of Aromatic Molecules
Attosecond X-Ray Core-Level Chronoscopy of Aromatic Molecules Open
Attosecond photoemission or photoionization delays are a unique probe of the structure and the electronic dynamics of matter. However, the spectral congestion of valence photoelectron spectra sets fundamental limits to the complexity of sy…
View article: Imaging Valence Electron Rearrangement in a Chemical Reaction Using Hard X-Ray Scattering
Imaging Valence Electron Rearrangement in a Chemical Reaction Using Hard X-Ray Scattering Open
We have observed the signatures of valence electron rearrangement in photoexcited ammonia using ultrafast hard x-ray scattering. Time-resolved x-ray scattering is a powerful tool for imaging structural dynamics in molecules because of the …
View article: Imaging a light-induced molecular elimination reaction with an X-ray free-electron laser
Imaging a light-induced molecular elimination reaction with an X-ray free-electron laser Open
Tracking the motion of individual atoms during chemical reactions represents a severe experimental challenge, especially if several competing reaction pathways exist or if the reaction is governed by the correlated motion of more than two …
View article: The time-resolved atomic, molecular and optical science instrument at the Linac Coherent Light Source. Corrigendum
The time-resolved atomic, molecular and optical science instrument at the Linac Coherent Light Source. Corrigendum Open
The name of an author in the article by Walter et al. (2022) [ J. Synchrotron Rad. 29 , 957–968] is corrected.
View article: Nonlinear reversal of photo-excitation on the attosecond time scale improves ultrafast x-ray diffraction images
Nonlinear reversal of photo-excitation on the attosecond time scale improves ultrafast x-ray diffraction images Open
The advent of isolated and intense sub-femtosecond X-ray pulses enables tracking of quantummechanical motion of electrons in molecules and solids. The combination of X-ray spectroscopy and diffraction imaging is a powerful approach to visu…
View article: Characterization of the LCLS-II X-rays with Imagers, Power Meters and Fluorescence Intensity Monitors
Characterization of the LCLS-II X-rays with Imagers, Power Meters and Fluorescence Intensity Monitors Open
The LCLS-II superconducting accelerator has begun operations and has been producing x-rays since August 2023. The current parameters are a photon energy range from 250 eV to 3.8 keV and a maximum repetition rate of 8.29 kHz. Imagers have d…
View article: Probing Electronic Coherence between Core-Level Vacancies at Different Atomic Sites
Probing Electronic Coherence between Core-Level Vacancies at Different Atomic Sites Open
The detailed understanding of electronic coherence in quantum systems requires measurements on the attosecond timescale. Attosecond x-ray pulses enable the study of electronic coherence in core-excited molecular systems. Here we report on …
View article: Design and performance of a magnetic bottle electron spectrometer for high-energy photoelectron spectroscopy
Design and performance of a magnetic bottle electron spectrometer for high-energy photoelectron spectroscopy Open
We describe the design and performance of a magnetic bottle electron spectrometer (MBES) for high-energy electron spectroscopy. Our design features a 2 m long electron drift tube and electrostatic retardation lens, achieving sub-electronvo…
View article: Covariance Analysis of Impulsive Streaking
Covariance Analysis of Impulsive Streaking Open
We present a comprehensive framework of modeling covariance in angular streaking experiments. Within the impulsive streaking regime, the displacement of electron momentum distribution (MD) provides a tight connection between the dressing-f…
View article: “Beam à la carte”: Laser heater shaping for attosecond pulses in a multiplexed x-ray free-electron laser
“Beam à la carte”: Laser heater shaping for attosecond pulses in a multiplexed x-ray free-electron laser Open
Electron beam shaping allows the control of the temporal properties of x-ray free-electron laser pulses from femtosecond to attosecond timescales. Here, we demonstrate the use of a laser heater to shape electron bunches and enable the gene…
View article: Attosecond Coherent Electron Motion in a Photoionized Aromatic Molecule
Attosecond Coherent Electron Motion in a Photoionized Aromatic Molecule Open
In molecular systems, the ultrafast motion of electrons initiates the process of chemical change. Tracking this electronic motion across molecules requires coupling attosecond time resolution to atomic-scale spatial sensitivity. In this wo…
View article: Attosecond impulsive stimulated X-ray Raman scattering in liquid water
Attosecond impulsive stimulated X-ray Raman scattering in liquid water Open
We report the measurement of impulsive stimulated x-ray Raman scattering in neutral liquid water. An attosecond pulse drives the excitations of an electronic wavepacket in water molecules. The process comprises two steps: a transition to c…
View article: Tracking dissociation pathways of nitrobenzene via mega-electron-volt ultrafast electron diffraction
Tracking dissociation pathways of nitrobenzene via mega-electron-volt ultrafast electron diffraction Open
As the simplest nitroaromatic compound, nitrobenzene is an interesting model system to explore the rich photochemistry of nitroaromatic compounds. Previous investigations of nitrobenzene’s photochemical dynamics have probed structural and …
View article: Attosecond delays in X-ray molecular ionization
Attosecond delays in X-ray molecular ionization Open
The photoelectric effect is not truly instantaneous but exhibits attosecond delays that can reveal complex molecular dynamics1-7. Sub-femtosecond-duration light pulses provide the requisite tools to resolve the dynamics of photoionization8…
View article: Design and Performance of a Magnetic Bottle Electron Spectrometer for High-Energy Photoelectron Spectroscopy
Design and Performance of a Magnetic Bottle Electron Spectrometer for High-Energy Photoelectron Spectroscopy Open
We describe the design and performance of a magnetic bottle electron spectrometer~(MBES) for high-energy electron spectroscopy. Our design features a ${\sim2}$~m long electron drift tube and electrostatic retardation lens, achieving sub-el…
View article: "Beam `a la carte": laser heater shaping for attosecond pulses in a multiplexed x-ray free-electron laser
"Beam `a la carte": laser heater shaping for attosecond pulses in a multiplexed x-ray free-electron laser Open
Electron beam shaping allows the control of the temporal properties of x-ray free-electron laser pulses from femtosecond to attosecond timescales. Here we demonstrate the use of a laser heater to shape electron bunches and enable the gener…
View article: Spectrotemporal shaping of attosecond x-ray pulses with a fresh-slice free-electron laser
Spectrotemporal shaping of attosecond x-ray pulses with a fresh-slice free-electron laser Open
We propose a scheme allowing coherent shaping, i.e., controlling both the amplitude and phase, of attosecond x-ray pulses at free-electron lasers. We show that by seeding an FEL with a short coherent seed that overfills the amplification b…
View article: Attosecond X-ray Core-level Chronoscopy of Aromatic Molecules
Attosecond X-ray Core-level Chronoscopy of Aromatic Molecules Open
Attosecond photoemission or photoionization delays are a unique probe of the structure and the electronic dynamics of matter. However, spectral congestion and spatial delocalization of valence electron wave functions set fundamental limits…
View article: Attosecond Delays in X-ray Molecular Ionization
Attosecond Delays in X-ray Molecular Ionization Open
The photoelectric effect is not truly instantaneous, but exhibits attosecond delays that can reveal complex molecular dynamics. Sub-femtosecond duration light pulses provide the requisite tools to resolve the dynamics of photoionization. A…
View article: Attosecond-pump attosecond-probe x-ray spectroscopy of liquid water
Attosecond-pump attosecond-probe x-ray spectroscopy of liquid water Open
Attosecond-pump/attosecond-probe experiments have long been sought as the most straightforward method for observing electron dynamics in real time. Although there has been much success with overlapped near-infrared femtosecond and extreme …
View article: Experimental Demonstration of Attosecond Pump-Probe Spectroscopy with an X-ray Free-Electron Laser
Experimental Demonstration of Attosecond Pump-Probe Spectroscopy with an X-ray Free-Electron Laser Open
Pump-probe experiments with sub-femtosecond resolution are the key to understanding electronic dynamics in quantum systems. Here we demonstrate the generation and control of sub-femtosecond pulse pairs from a two-colour X-ray free-electron…
View article: Free Electron Lasers for X-ray Scattering and Diffraction
Free Electron Lasers for X-ray Scattering and Diffraction Open
Since their discovery more than 100 years ago, X-rays have transformed our understanding of the fundamental structure of matter. They have become an indispensable tool for materials science, biology, chemistry, physics, and many related fi…
View article: Efficient prediction of attosecond two-colour pulses from an X-ray free-electron laser with machine learning
Efficient prediction of attosecond two-colour pulses from an X-ray free-electron laser with machine learning Open
X-ray free-electron lasers are sources of coherent, high-intensity X-rays with numerous applications in ultra-fast measurements and dynamic structural imaging. Due to the stochastic nature of the self-amplified spontaneous emission process…
View article: Femtosecond Electronic and Hydrogen Structural Dynamics in Ammonia Imaged with Ultrafast Electron Diffraction
Femtosecond Electronic and Hydrogen Structural Dynamics in Ammonia Imaged with Ultrafast Electron Diffraction Open
Directly imaging structural dynamics involving hydrogen atoms by ultrafast diffraction methods is complicated by their low scattering cross sections. Here we demonstrate that megaelectronvolt ultrafast electron diffraction is sufficiently …
View article: Compact single-shot soft X-ray photon spectrometer for free-electron laser diagnostics
Compact single-shot soft X-ray photon spectrometer for free-electron laser diagnostics Open
The photon spectrum from free-electron laser (FEL) light sources offers valuable information in time-resolved experiments and machine optimization in the spectral and temporal domains. We have developed a compact single-shot photon spectro…
View article: Investigating dissociation pathways of nitrobenzene via mega-electron-volt ultrafast electron diffraction
Investigating dissociation pathways of nitrobenzene via mega-electron-volt ultrafast electron diffraction Open
As the simplest nitroaromatic compound, nitrobenzene is an interesting model system to explore the rich photochemistry of nitroaromatic compounds. Previous measurements of nitrobenzene's photochemical dynamics have probed structural and el…