All Publications

  • Femtosecond Visualization of hcp-Iron Strength and Plasticity under Shock Compression. Physical review letters Merkel, S., Hok, S., Bolme, C., Rittman, D., Ramos, K. J., Morrow, B., Lee, H. J., Nagler, B., Galtier, E., Granados, E., Hashim, A., Mao, W. L., Gleason, A. E. 2021; 127 (20): 205501


    Iron is a key constituent of planets and an important technological material. Here, we combine insitu ultrafast x-ray diffraction with laser-induced shock compression experiments on Fe up to 187(10)GPa and 4070(285)K at 10^{8}s^{-1} in strain rate to study the plasticity of hexagonal-close-packed (hcp)-Fe under extreme loading states. {101[over ]2} deformation twinning controls the polycrystalline Fe microstructures and occurs within 1ns, highlighting the fundamental role of twinning in hcp polycrystals deformation at high strain rates. The measured deviatoric stress initially increases to a significant elastic overshoot before the onset of flow, attributed to a slower defect nucleation and mobility. The initial yield strength of materials deformed at high strain rates is thus several times larger than their longer-term flow strength. These observations illustrate how time-resolved ultrafast studies can reveal distinctive plastic behavior in materials under extreme environments.

    View details for DOI 10.1103/PhysRevLett.127.205501

    View details for PubMedID 34860050

  • Ultrafast X-ray Diffraction Study of a Shock-Compressed Iron Meteorite above 100 GPa MINERALS Tecklenburg, S., Colina-Ruiz, R., Hok, S., Bolme, C., Galtier, E., Granados, E., Hashim, A., Lee, H., Merkel, S., Morrow, B., Nagler, B., Ramos, K., Rittman, D., Walroth, R., Mao, W. L., Gleason, A. E. 2021; 11 (6)
  • Ronchi shearing interferometry for wavefronts with circular symmetry JOURNAL OF SYNCHROTRON RADIATION Nagler, B., Galtier, E. C., Brown, S. B., Heimann, P., Dyer, G., Lee, H. 2020; 27: 1461–69


    Ronchi testing of a focused electromagnetic wave has in the last few years been used extensively at X-ray free-electron laser (FEL) facilities to qualitatively evaluate the wavefront of the beam. It is a quick and straightforward test, is easy to interpret on the fly, and can be used to align phase plates that correct the focus of aberrated beams. In general, a single Ronchigram is not sufficient to gain complete quantitative knowledge of the wavefront. However the compound refractive lenses that are commonly used at X-ray FELs exhibit a strong circular symmetry in their aberration, and this can be exploited. Here, a simple algorithm that uses a single recorded Ronchigram to recover the full wavefront of a nano-focused beam, assuming circular symmetry, is presented, and applied to experimental measurements at the Matter in Extreme Conditions instrument at the Linac Coherent Light Source.

    View details for DOI 10.1107/S1600577520010735

    View details for Web of Science ID 000588645400001

    View details for PubMedID 33147170

  • In situ X-ray diffraction of silicate liquids and glasses under dynamic and static compression to megabar pressures. Proceedings of the National Academy of Sciences of the United States of America Morard, G. n., Hernandez, J. A., Guarguaglini, M. n., Bolis, R. n., Benuzzi-Mounaix, A. n., Vinci, T. n., Fiquet, G. n., Baron, M. A., Shim, S. H., Ko, B. n., Gleason, A. E., Mao, W. L., Alonso-Mori, R. n., Lee, H. J., Nagler, B. n., Galtier, E. n., Sokaras, D. n., Glenzer, S. H., Andrault, D. n., Garbarino, G. n., Mezouar, M. n., Schuster, A. K., Ravasio, A. n. 2020


    Properties of liquid silicates under high-pressure and high-temperature conditions are critical for modeling the dynamics and solidification mechanisms of the magma ocean in the early Earth, as well as for constraining entrainment of melts in the mantle and in the present-day core-mantle boundary. Here we present in situ structural measurements by X-ray diffraction of selected amorphous silicates compressed statically in diamond anvil cells (up to 157 GPa at room temperature) or dynamically by laser-generated shock compression (up to 130 GPa and 6,000 K along the MgSiO3 glass Hugoniot). The X-ray diffraction patterns of silicate glasses and liquids reveal similar characteristics over a wide pressure and temperature range. Beyond the increase in Si coordination observed at 20 GPa, we find no evidence for major structural changes occurring in the silicate melts studied up to pressures and temperatures exceeding Earth's core mantle boundary conditions. This result is supported by molecular dynamics calculations. Our findings reinforce the widely used assumption that the silicate glasses studies are appropriate structural analogs for understanding the atomic arrangement of silicate liquids at these high pressures.

    View details for DOI 10.1073/pnas.1920470117

    View details for PubMedID 32414927

  • Focal Spot and Wavefront Sensing of an X-Ray Free Electron laser using Ronchi shearing interferometry SCIENTIFIC REPORTS Nagler, B., Aquila, A., Boutet, S., Galtier, E. C., Hashim, A., Hunter, M. S., Liang, M., Sakdinawat, A. E., Schroer, C. G., Schropp, A., Seaberg, M. H., Seiboth, F., van Driel, T., Xing, Z., Liu, Y., Lee, H. 2017; 7: 13698


    The Linac Coherent Light Source (LCLS) is an X-ray source of unmatched brilliance, that is advancing many scientific fields at a rapid pace. The highest peak intensities that are routinely produced at LCLS take place at the Coherent X-ray Imaging (CXI) instrument, which can produce spotsize at the order of 100 nm, and such spotsizes and intensities are crucial for experiments ranging from coherent diffractive imaging, non-linear x-ray optics and high field physics, and single molecule imaging. Nevertheless, a full characterisation of this beam has up to now not been performed. In this paper we for the first time characterise this nanofocused beam in both phase and intensity using a Ronchi Shearing Interferometric technique. The method is fast, in-situ, uses a straightforward optimization algoritm, and is insensitive to spatial jitter.

    View details for DOI 10.1038/s41598-017-13710-8

    View details for Web of Science ID 000413357500064

    View details for PubMedID 29057938

    View details for PubMedCentralID PMC5651859

  • Shock drive capabilities of a 30-Joule laser at the matter in extreme conditions hutch of the Linac Coherent Light Source REVIEW OF SCIENTIFIC INSTRUMENTS Brown, S., Hashim, A., Gleason, A., Galtier, E., Nam, I., Xing, Z., Fry, A., MacKinnon, A., Nagler, B., Granados, E., Lee, H. 2017; 88 (10): 105113


    We measure the shock drive capabilities of a 30 J, nanosecond, 527 nm laser system at the matter in extreme conditions hutch of the Linac Coherent Light Source. Using a velocity interferometer system for any reflector, we ascertain the maximum instantaneous ablation pressure and characterize its dependence on a drive laser spot size, spatial profile, and temporal profile. We also examine the effects of these parameters on shock spatial and temporal uniformity. Our analysis shows the drive laser capable of generating instantaneous ablation pressures exceeding 160 GPa while maintaining a 1D shock profile. We find that slope pulses provide higher instantaneous ablation pressures than plateau pulses. Our results show instantaneous ablation pressures comparable to those measured at the Omega Laser Facility in Rochester, NY under similar optical drive parameters. Finally, we analyze how optical laser ablation pressures are compare with known scaling relations, accounting for variable laser wavelengths.

    View details for PubMedID 29092479

  • The phase-contrast imaging instrument at the matter in extreme conditions endstation at LCLS REVIEW OF SCIENTIFIC INSTRUMENTS Nagler, B., Schropp, A., Galtier, E. C., Arnold, B., Brown, S. B., Fry, A., Gleason, A., Granados, E., Hashim, A., Hastings, J. B., Samberg, D., Seiboth, F., Tavella, F., Xing, Z., Lee, H. J., Schroer, C. G. 2016; 87 (10)


    We describe the phase-contrast imaging instrument at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source. The instrument can image phenomena with a spatial resolution of a few hundreds of nanometers and at the same time reveal the atomic structure through X-ray diffraction, with a temporal resolution better than 100 fs. It was specifically designed for studies relevant to high-energy-density science and can monitor, e.g., shock fronts, phase transitions, or void collapses. This versatile instrument was commissioned last year and is now available to the MEC user community.

    View details for DOI 10.1063/1.4963906

    View details for Web of Science ID 000387661900033

    View details for PubMedID 27802688

  • Bent crystal spectrometer for both frequency and wavenumber resolved x-ray scattering at a seeded free-electron laser REVIEW OF SCIENTIFIC INSTRUMENTS Zastrau, U., Fletcher, L. B., Foerster, E., Galtier, E. C., Gamboa, E., Glenzer, S. H., Heimann, P., Marschner, H., Nagler, B., Schropp, A., Wehrhan, O., Lee, H. J. 2014; 85 (9)


    We present a cylindrically curved GaAs x-ray spectrometer with energy resolution ΔE/E = 1.1 × 10(-4) and wave-number resolution of Δk/k = 3 × 10(-3), allowing plasmon scattering at the resolution limits of the Linac Coherent Light Source (LCLS) x-ray free-electron laser. It spans scattering wavenumbers of 3.6 to 5.2/Å in 100 separate bins, with only 0.34% wavenumber blurring. The dispersion of 0.418 eV/13.5 μm agrees with predictions within 1.3%. The reflection homogeneity over the entire wavenumber range was measured and used to normalize the amplitude of scattering spectra. The proposed spectrometer is superior to a mosaic highly annealed pyrolytic graphite spectrometer when the energy resolution needs to be comparable to the LCLS seeded bandwidth of 1 eV and a significant range of wavenumbers must be covered in one exposure.

    View details for DOI 10.1063/1.4894821

    View details for Web of Science ID 000342910500007