A5082391461- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Magnetic and transport properties of perovskites and related materials
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- High-pressure geophysics and materials
- Superconducting Materials and Applications
- Electronic and Structural Properties of Oxides
- Semiconductor Quantum Structures and Devices
- Advanced X-ray Imaging Techniques
- Quantum, superfluid, helium dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Porphyrin Metabolism and Disorders
- Inorganic Fluorides and Related Compounds
- Enzyme Structure and Function
- Electrohydrodynamics and Fluid Dynamics
- Characterization and Applications of Magnetic Nanoparticles
- Biocrusts and Microbial Ecology
- Superconductivity in MgB2 and Alloys
- Mass Spectrometry Techniques and Applications
- Advanced Electron Microscopy Techniques and Applications
- Semiconductor materials and devices
- Signaling Pathways in Disease
SLAC National Accelerator Laboratory
2016-2024
Linac Coherent Light Source
2016-2024
SPring-8
2019
Bioengineering Center
2019
Kyoto University
2019
High Energy Accelerator Research Organization
2019
Menlo School
2018
Lawrence Berkeley National Laboratory
2009-2016
University of California, Berkeley
2011
University of Colorado Boulder
2003-2008
Visualizing a response to light Many biological processes depend on detecting and responding light. The is often mediated by structural change in protein that begins when absorption of photon causes isomerization chromophore bound the protein. Pande et al. used x-ray pulses emitted free electron laser source conduct time-resolved serial femtosecond crystallography time range 100 fs 3 ms. This allowed for real-time tracking trans-cis photoactive yellow associated changes Science , this issue p. 725
In this supporting material for the main paper (the preceding submission), we show, in addition to related information experiments, additional discussion that cannot fit (due space constraint). It includes further about our experimental observations, wider implications of findings with various reported candidates pseudogap order, and a simple mean-field argument favors interpretations based on finite-Q order (density wave) seen by ARPES (whether "the order" is single or contains multiple...
The “hole” story of water ionization direct observation the cationic hole H 2 O + that is formed in liquid after has been a long-standing experimental challenge. Previous attempts using optical and ultraviolet techniques have failed to reveal its key spectroscopic signature during ultrafast transformation into OH radical. Loh et al. address this gap by intense, x-ray pulses from an free electron laser at ∼530 volts. They found compelling evidence for formation decay radical proton transfer...
Attosecond-pump/attosecond-probe experiments have long been sought as the most straightforward method for observing electron dynamics in real time. Although there has much success with overlapped near-infrared femtosecond and extreme ultraviolet attosecond pulses combined theory, true attosecond-pump/attosecond-probe limited. We used a synchronized x-ray pulse pair from an free-electron laser to study electronic response valence ionization liquid water through all transient absorption...
In high-temperature superconductivity, the process that leads to formation of Cooper pairs, fundamental charge carriers in any superconductor, remains mysterious. We used a femtosecond laser pump pulse perturb superconducting Bi(2)Sr(2)CaCu(2)O(8+δ) and studied subsequent dynamics using time- angle-resolved photoemission infrared reflectivity probes. Gap quasiparticle population revealed marked dependencies on both excitation density crystal momentum. Close d-wave nodes, gap was sensitive...
A new low photon energy regime of angle-resolved photoemission spectroscopy is accessed with lasers and used to study the high T(C) superconductor Bi2Sr2CaCu2O(8+delta). The increases bulk sensitivity, reduces background, improves resolution. With this we observe spectral peaks which are sharp on scale their binding energy--the clearest evidence yet for quasiparticles in normal state. Crucial aspects data such as dispersion, superconducting gaps, bosonic coupling kink found be robust a...
The physics and chemistry of liquid solutions play a central role in science, our understanding life on Earth. Unfortunately, key tools for interrogating aqueous systems, such as infrared soft X-ray spectroscopy, cannot readily be applied because strong absorption water. Here we use gas-dynamic forces to generate free-flowing, sub-micron, sheets which are two orders magnitude thinner than anything previously reported. Optical, infrared, spectroscopies used characterize the sheets, found...
Superconductivity and charge density waves (CDWs) are competitive, yet coexisting, orders in cuprate superconductors. To understand their microscopic interdependence, a probe capable of discerning interaction on its natural length time scale is necessary. We use ultrafast resonant soft x-ray scattering to track the transient evolution CDW correlations YBa2Cu3O6+x after quench superconductivity by an infrared laser pulse. observe nonthermal response order characterized near doubling...
Using high-resolution angle-resolved photoemission spectroscopy on $Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta}$, we have made the first observation of a mass renormalization or "kink" in E vs. $\vec k$ dispersion relation localized near $(\pi, 0)$. Compared to kink observed along nodal direction, this new effect is clearly stronger, appears at lower energy 40 meV, and only present superconducting state. The scale defines cutoff below which well-defined quasiparticle excitations occur. This likely due...
Abstract The dynamics of liquid water feature a variety time scales, ranging from extremely fast ballistic-like thermal motion, to slower molecular diffusion and hydrogen-bond rearrangements. Here, we utilize coherent X-ray pulses investigate the sub-100 fs equilibrium ambient conditions down supercooled temperatures. This novel approach utilizes inherent capability speckle visibility spectroscopy measure intermolecular with lengthscale selectivity, by measuring oxygen motion in momentum...
Ultrafast, polarization-selective time-resolved X-ray absorption near-edge structure (XANES) was used to characterize the photochemistry of vitamin B12, cyanocobalamin (CNCbl), in solution. Cobalamins are important biological cofactors involved methyl transfer, radical rearrangement, and light-activated gene regulation, while also holding promise as agents for spatiotemporal controlled delivery therapeutics. We introduce polarized femtosecond XANES, combined with UV–visible spectroscopy,...
We report the observation and analysis of gain curve amplified Kα x-ray emission from solutions Mn(II) Mn(VII) complexes using an free electron laser to create 1s core-hole population inversion. find spectra at amplification levels extending over 4 orders magnitude until saturation. observe bandwidths below Mn lifetime broadening in onset stimulated emission. In exponential regime resolution corrected spectral width ∼1.7 eV FWHM is constant 3 magnitude, pointing buildup transform limited...
We report the observation of coherent oscillations associated with charge-density-wave (CDW) order in underdoped cuprate superconductor YBa${}_{2}$Cu${}_{3}$O${}_{6+x}$ by time-resolved optical reflectivity. Oscillations frequency $1.87$ THz onset at approximately 105 and 130 K for dopings $x=0.67$ (ortho-VIII) $x=0.75$ (ortho-III), respectively. Upon cooling below superconducting critical temperature (${T}_{c}$), oscillation amplitude is enhanced, phase shifts $\ensuremath{\pi}$, softens...
We report an x-ray photon correlation spectroscopy method that exploits the recent development of two-pulse mode at Linac Coherent Light Source. By using coherent resonant magnetic scattering, we studied spontaneous fluctuations on nanosecond time scales in thin films multilayered Fe/Gd exhibit ordered stripe and Skyrmion lattice phases. The was found to differ between phase near stripe-Skyrmion boundary. This technique will enable a significant new area research study equilibrium condensed matter.
Resonant inelastic x-ray scattering (RIXS) provides remarkable opportunities to interrogate ultrafast dynamics in liquids. Here we use RIXS study the fundamentally and practically important hydroxyl radical liquid water, OH(aq). Impulsive ionization of pure water produced a short-lived population OH(aq), which was probed using femtosecond x-rays from an free-electron laser. We find that reveals localized electronic transitions are masked ultraviolet absorption spectrum by strong...
We present time-resolved X-ray absorption spectra of ionized liquid water and demonstrate that OH radicals, H3O+ ions, solvated electrons all leave distinct X-ray-spectroscopic signatures. Particularly, this allows us to characterize the electron solvation process through a tool focuses on electronic response oxygen atoms in immediate vicinity electron. Our experimental results, supported by ab initio calculations, confirm formation cavity which is trapped. show dynamics are governed...
Abstract Phytochromes are a family of photoreceptors that control light responses plants, fungi and bacteria. A sequence structural changes, which is not yet fully understood, leads to activation an output domain. Time-resolved serial femtosecond crystallography (SFX) can potentially shine on these conformational changes. Here we report the room temperature crystal structure chromophore-binding domains Deinococcus radiodurans phytochrome at 2.1 Å resolution. The was obtained by X-ray from...
Innovative new crystallographic methods are facilitating structural studies from ever smaller crystals of biological macromolecules. In particular, serial X-ray crystallography and microcrystal electron diffraction (MicroED) have emerged as useful for obtaining information on the nanometre to micrometre scale. Despite utility these methods, their implementation can often be difficult, they present many challenges that not encountered in traditional macromolecular experiments. Here, XFEL...
A laser-based angle resolved photoemission (ARPES) system utilizing 6 eV photons from the fourth harmonic of a mode-locked Ti:sapphire oscillator is described. This light source greatly increases momentum resolution and photoelectron count rate, while reducing extrinsic background surface sensitivity relative to higher energy sources. In this review, optical described, special experimental considerations for low-energy ARPES are discussed. The calibration hemispherical electron analyzer good...
Using low photon energy angle-resolved photoemission, we study the low-energy dispersion along nodal ($\ensuremath{\pi},\ensuremath{\pi}$) direction in ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ as a function of temperature. Less than 10 meV below Fermi energy, high-resolution data reveal novel ``kinklike'' feature electron self-energy that is distinct from larger well-known kink roughly 70 ${E}_{F}$. This new strongest superconducting...
We have used transient absorption spectroscopy in the UV–visible and X-ray regions to characterize excited state of CarH, a protein photoreceptor that uses form B12, adenosylcobalamin (AdoCbl), sense light. With visible excitation, nanosecond-lifetime photoactive is formed with unit quantum yield. The time-resolved near edge structure difference spectrum this demonstrates AdoCbl CarH undergoes only modest structural expansion around central cobalt, behavior similar observed for...
The high intensity of X-ray free electron lasers (XFELs) can damage solution-phase samples on every scale, ranging from the molecular or electronic structure a sample to macroscopic liquid microjet. By using large surface area sheet microjet as target instead standard cylindrical microjet, incident spot size be increased such that falls below threshold. This capability is becoming particularly important for repetition rate XFELs, where destroying with each pulse would require prohibitively...
We use pump-probe spectroscopy to measure the photoinduced reflectivity $\ensuremath{\Delta}R$ of electron-doped cuprate superconductor ${\mathrm{Nd}}_{2\ensuremath{-}x}{\mathrm{Ce}}_{x}{\mathrm{CuO}}_{4+\ensuremath{\delta}}$ at a value $x$ near optimal doping, as function time, temperature, and laser fluence. observe onset negative signal ${T}^{*}\ensuremath{\approx}75\text{ }\text{ }\mathrm{K}$, above superconducting transition ${T}_{c}$, 23 K. The relatively slow decay...