Sub-micron thick liquid sheets produced by isotropically etched glass nozzles.
Lab on a chip
We report on the design and testing of glass nozzles used to produce liquid sheets. The sheet nozzles use a single converging channel chemically etched into glass wafers by standard lithographic methods. Operation in ambient air and vacuum was demonstrated. The measured sheet thickness ranges over one order of magnitude with the smallest thickness of 250 nm and the largest of 2.5 mum. Sheet thickness was shown to be independent of liquid flow rate, and dependent on the nozzle outlet area. Sheet surface roughness was dependent on nozzle surface finish and was on the order of 10 nm for polished nozzles. Electron transmission data is presented for various sheet thicknesses near the MeV mean free path and the charge pair distribution function for D2O is determined from electron scattering data.
View details for DOI 10.1039/d1lc00757b
View details for PubMedID 35234235
Ultrafast visualization of incipient plasticity in dynamically compressed matter.
2022; 13 (1): 1055
Plasticity is ubiquitous and plays a critical role in material deformation and damage; it inherently involves the atomistic length scale and picosecond time scale. A fundamental understanding of the elastic-plastic deformation transition, in particular, incipient plasticity, has been a grand challenge in high-pressure and high-strain-rate environments, impeded largely by experimental limitations on spatial and temporal resolution. Here, we report femtosecond MeV electron diffraction measurements visualizing the three-dimensional (3D) response of single-crystal aluminum to the ultrafast laser-induced compression. We capture lattice transitioning from a purely elastic to a plastically relaxed state within 5 ps, after reaching an elastic limit of~25 GPa. Our results allow the direct determination of dislocation nucleation and transport that constitute the underlying defect kinetics of incipient plasticity. Large-scale molecular dynamics simulations show good agreement with the experiment and provide an atomic-level description of the dislocation-mediated plasticity.
View details for DOI 10.1038/s41467-022-28684-z
View details for PubMedID 35217665
- Effect of lattice excitations on transient near-edge x-ray absorption spectroscopy PHYSICAL REVIEW B 2021; 104 (14)
- Imaging the short-lived hydroxyl-hydronium pair in ionized liquid water. Science (New York, N.Y.) 2021; 374 (6563): 92-95
- Observation of a highly conductive warm dense state of water with ultrafast pump-probe free-electron-laser measurements MATTER AND RADIATION AT EXTREMES 2021; 6 (5)
- Fast attenuation of high-frequency acoustic waves in bicontinuous nanoporous gold APPLIED PHYSICS LETTERS 2021; 119 (6)
- Ultrafast visualization of phase transitions in nonequilibrium warm dense matter MRS BULLETIN 2021
Direct observation of ultrafast hydrogen bond strengthening in liquid water.
2021; 596 (7873): 531-535
Water is one of the most important, yet least understood, liquids in nature. Many anomalous properties of liquid water originate from its well-connected hydrogen bond network1, including unusually efficient vibrational energy redistribution and relaxation2. An accurate description of the ultrafast vibrational motion of water molecules is essential for understanding the nature of hydrogen bonds and many solution-phase chemical reactions. Most existing knowledge of vibrational relaxation in water is built upon ultrafast spectroscopy experiments2-7. However, these experiments cannot directly resolve the motion of the atomic positions and require difficult translation of spectral dynamics into hydrogen bond dynamics. Here, we measure the ultrafast structural response to the excitation of the OH stretching vibration in liquid water with femtosecond temporal and atomic spatial resolution using liquid ultrafast electron scattering. We observed a transient hydrogen bond contraction of roughly 0.04A on a timescale of 80 femtoseconds, followed by a thermalization on a timescale of approximately 1 picosecond. Molecular dynamics simulations reveal the need to treat the distribution of the shared proton in the hydrogen bond quantum mechanically to capture the structural dynamics on femtosecond timescales. Our experiment and simulations unveil the intermolecular character of the water vibration preceding the relaxation of the OH stretch.
View details for DOI 10.1038/s41586-021-03793-9
View details for PubMedID 34433948
Structure retrieval in liquid-phase electron scattering.
Physical chemistry chemical physics : PCCP
Electron scattering on liquid samples has been enabled recently by the development of ultrathin liquid sheet technologies. The data treatment of liquid-phase electron scattering has been mostly reliant on methodologies developed for gas electron diffraction, in which theoretical inputs and empirical fittings are often needed to account for the atomic form factor and remove the inelastic scattering background. In this work, we present an alternative data treatment method that is able to retrieve the radial distribution of all the charged particle pairs without the need of either theoretical inputs or empirical fittings. The merits of this new method are illustrated through the retrieval of real-space molecular structure from experimental electron scattering patterns of liquid water, carbon tetrachloride, chloroform, and dichloromethane.
View details for DOI 10.1039/d0cp06045c
View details for PubMedID 33367391
- Synthesis of Macroscopic Single Crystals of Ge2Sb2Te5 via Single-Shot Femtosecond Optical Excitation CRYSTAL GROWTH & DESIGN 2020; 20 (10): 6660–67
- Characterization of defect clusters in ion-irradiated tungsten by X-Ray diffuse scattering JOURNAL OF NUCLEAR MATERIALS 2018; 510: 322–30