XDL2011 Workshop 4 Abstracts

High-pressure Science at the Edge of Feasibility
Thursday, June 23rd - Friday, June 24th, 2011

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Organizers: Russell J. Hemley (Carnegie Institute of Washington), Neil Ashcroft (Cornell University), Roald Hoffmann (Cornell University), John Parise (SUNY Stony Brook), Zhongwu Wang (Cornell University)

Workshop Agenda (html)

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Energy Recovery Linac (ERL) and Ultimate Storage Ring (USR) Properties

Don Bilderback
Cornell University

ERLs and USRs are under consideration for next generation, high-duty cycle (>MHz rep rates), coherent x-rays sources. They both feature extremely high average spectral brightness, diffraction-limited performance and are the response to 3rd generation storage ring users/developers who would like "more x-ray flux, smaller x-ray beam size, more coherent x-ray flux on sample, higher energy resolution probes and/or short pulses for repetitive probing". In most cases, the x-ray beam should minimally impact the sample under study. We review the general features of ERLs and USRs in the context of the Cornell ERL and PEP-X as two well-developed examples from the x-ray community. Additionally, examples of utilization of the advanced properties of these machines will be given. The first example explores using the timing structure to repetitively probe the response of x-ray excited optical luminescence. The second uses the extremely high average brightness to conceptually develop ideas toward a confocal x-ray microscope that is designed to image single atoms based on either Thompson scattering or x-ray fluorescence.

X-ray Detectors: State-of-the-art & Future Possibilities

Sol Gruner
Cornell University

The state-of-the-art of quantitative imaging x-ray detectors is described. We then consider upcoming technologies that may be applied to imaging detectors to advance the state-of-the-art with respect to pixel size and functionality, spatial resolution, time resolution, analog dynamic range, and energy resolution. Specifically, we look into our crystal ball and ask what is likely feasible on a decade time scale, given adequate R&D, given current physical limits of materials and technology.

Addressing Emergent Issues in High Pressure Research

John Parise
Stony Brook University

I will present a personal inventory of a couple emergent issues that may be of interest to a broader audience of condensed matter scientists. Experimental approaches to "The deepest and most interesting unsolved problem in solid state theory (the glass transition as described by P.W. Anderson (1995), "Through the Glass Lightly", Science 267: 1615) show new signs of life with literature surveys and scattering experiments suggesting a cross-over point in the behavior of cooling melts. If this crossover from linear to non-linear behavior is universal, then its structural origin, and especially its dependence on PT-conditions, cooling rate etc. should be targets for more intense study. Time resolved high energy x-ray scattering, supplemented by selected studies using isotopic substitution neutron scattering, would remain the most reliable means to determine local structure. Liquids at extreme conditions are of course in general interesting - from those that are pressure stabilized, to those deeply under-cooled, to water ropes forming at high voltage. In all cases the collection of reliable time resolved scattering data, both elastic and inelastic if possible, is required to match local atomic arrangements to properties. It will be crucial to couple theory with the experimental x-ray developments, and this is being done, for example in the liquid/glassy metals community (Egami, JOM, 2010; PRL, 2011, 106).

Coupling theoretical prediction to identify targets for high pressure synthesis with in situ scattering, could provide viable starting points to take us beyond "random walks" through the periodic table in search of new functional materials. The development of methodologies to speed the discovery cycle for novel functional materials recoverable from HP synthesis, will require in situ measurement of processes on several length scales, Å-nm-µm, as proposed by Poulsen (Tracts in Modern Physics, 2004) at ambient pressure, and the simultaneous use of probes to measure properties.

Resonant Coherent X-ray Imaging

Yusheng Zhao
University of Nevada at Las Vegas

High-pressure synchrotron x-ray diffraction, spectroscopy, and tomography technologies can be applied in the research fields of renewable energy exploration, carbon dioxide sequestration, hydrogen storage, thermoelectrics and battery development, etc. For example, (1) in-situ/real-time study of fast-ionic conducting of battery material with electric charge/discharge; (2) structural mechanisms, thermodynamic stability, and reaction kinetics of H2 sorption and desorption; (3) radiography/tomography monitoring of super-critical CO2 reaction with the geo-hydrological settings in changes of porosity, permeability, and mineralogy, etc. Better understanding of thermoelectrics, superhard and ultratough mechanisms, solar photon-electron transferring, and biomass hydrocarbon conversions can all be gained through high-P synchrotron x-ray studies. The studies of Energy Materials call for the development of an integrated x-ray beamline to combine the techniques of diffraction, spectroscopy, tomography at pressure and temperature conditions. It is commonly recognized that the investments in this particular science and technology prospect will result in high impacts of societal development.

Dynamic Compression of Condensed Matter: Need for Time-Resolved Measurements

Yogendra Gupta
Washington State University

Shock wave and shockless compression experiments subject materials to extreme compressions, broad range of temperatures, and large deformations for very short times (tens of ps to hundreds of ns). Major advances in experimental capabilities in the past decade (e.g., laser and pulsed power platforms) can provide well defined, plane wave loading to access density-temperature-time conditions previously unattainable. Mechanistic understanding of the resulting time-dependent physical and chemical phenomena in these experiments constitutes an important and exciting challenge, and will require time-resolved measurements at different length scales. Per the Workshop objectives, this talk will focus on scientific motivation, challenges, and potential approaches to probe condensed matter dynamics in real time in dynamic compression experiments.

Synchrotron Techniques, X-ray Tomography and Imaging Through DAC

Wenge Yang
Advanced Photon Source

For in-situ high pressure research, traditionally the x-ray diffraction and spectroscopy are the two major tools. The newly developed x-ray tomography technique (TXM) has achieved 3d 30 nm spatial resolution for detail microstructure studies in-situ. We have overcome several technique constrains, and applied the full-field imaging method to study the materials under high pressure in diamond anvil cells and combined with x-ray diffraction method to study the lattice prefer orientation, shape correlation, equation of state, phase transition as a function of pressure. A parallel imaging technique using the coherent diffraction (CDI) method has also been developed at HPSynC. Three dimensional strain field in single crystal nanoparticles in DACs has been measured for the first time, which open a new way to explore material response under high pressure. Both techniques mentioned above will largely benefit from the new capabilities of ERL coherent hard x-ray sources, which will provide smaller source emittance and great coherence. In this talk, we will present the current status, development goals and outlook the future directions, especially with ERL sources.

Time- and Angle-Resolved Powder X-ray Diffraction to Probe Structural and Chemical Evolutions of Single-Event Phenomena

Choong-Shik Yoo
Washington State University

We present novel time- and angle-resolved powder x-ray diffraction capable of probing structural and chemical evolutions during rapidly propagating exothermic reactions of metallic solids. The system utilizes monochromatic synchrotron x-rays and a twodimensional (2D) pixel array x-ray detector in combination of a fast-rotating diffraction beam chopper, providing a time (in azimuth) and angle (in distance) -resolved x-ray diffraction image continuously recorded at a time resolution of ~30 μs over a time period of 3 ms. The present method is applicable to a wide range of dynamic experiments to study both single event phenomena of solids under thermal, electric or mechanical impact conditions and non-single event changes using dynamic-DAC and high frequency pulse lasers and is synergistic to many proposed activities to develop dynamic synchrotron x-ray diffraction capabilities, centered at third (APS, NSLS-II, PETRA-III)- and fourth (LCLS, ERL)- generation light sources.

Static and Dynamic Heating of Materials

Reinhard Boehler
Carnegie Institute of Washington

We are developing new experimental techniques to solve the large discrepancies in the melting curves of refractory transition metals (W, Ta, Mo etc.) measured statically in the laser-heated diamond cell and in shock experiments. The new methods employ "single-shot" laser heating in order to reduce problems associated with mechanical instabilities and chemical reactions of the samples subjected to several thousand degrees at megabar pressures. For melt detection, both synchrotron X-ray diffraction and Scanning Electron Microscopy (SEM) on recovered samples are used. A third approach is the measurement of latent heat effects associated with melting or freezing. This method employs simultaneous CW and pulse laser heating and monitoring the temperature-time history with fast photomultipliers. Using the SEM recovery method, we measured first melting temperatures of rhenium, which at high pressure may be one of the most refractory m

Structure and Stability of Low-Z Materials at Extreme Pressure and Temperature

Stanimir Bonev
Lawrence Livermore National Laboratory

The stability of materials under extreme pressure and temperature conditions often depends on a delicate balance between various energy terms. Minor variations in their relative significance, either spurious as a result of theoretical inaccuracies, or due to changes in the physical and chemical environments, can lead to dramatic phase transitions. In some cases, striking phenomena can be explained with subtle changes in microscopic structure and electronic properties. While on one hand this puts strict requirements for the accuracy of the theory used to predict high-pressure phenomena, standard methods valid at ambient conditions may begin to fail at the extreme. In this context, x-ray data from ultra-bright sources could provide invaluable help for validating and guiding the theoretical studies. I will give examples from our recent research where a synergy between theory and state-of-the art x-ray diffraction measurements could resolve the high-pressure properties of low-Z materials.

Hydrogen Under Extreme Pressure

Isaac Silvera
Harvard University

One of the great challenges of condensed matter physics is to produce solid hydrogen in the metallic phase, predicted by Wigner and Huntington over 75 years ago. At pressures exceeding 3 megabars solid hydrogen remains an insulator, although shock wave experiments have produced it in a conducting liquid state at lower pressures. A large number of theoretical predictions or speculations exist for the metallic state including that it may be a room temperature superconductor, metastably remain in the metallic state when the pressure is released, become a liquid metal at multimegabar pressures and zero Kelvin temperature where it would be a two component superconductor (electrons and mobile protons) as well as a superfluid. A measurement approach that would marry both the higher static pressures achieved in a diamond anvil cell and the high temperatures in a shock experiment, is to pulse laser heat or shock compress high pressure hydrogen to high temperatures and with the ERL measure the properties and states of the solid, the liquid and the atoms (mono or molecular) over a broad regime of P and T.

Time-domain Measurements in Diamond Anvil Cells

Alexander Goncharov
Carnegie Institution of Washington

We currently lack understanding of the full range of chemical and physical processes that occur in materials under extremes of high pressure, high temperature, and high strain rates. Here I address the need for a suite of time-resolved techniques for creating high pressure, temperature, and stress rate conditions in materials and for interrogating the materials subjected to these states with advanced diagnostics. Currently, there is a gap in pressure-temperature-strain rate conditions between those reached and probed in static (diamond-anvil cell) and dynamic (shock-wave) high-pressure experiments. Moreover, the existing diagnostic techniques are often scarce in determining in situ material structure, bonding state, electronic structure, and chemical reactivity at such extreme conditions. In order to address the complexity of the dynamic phenomena of materials under a wide range of thermodynamic conditions and spatial and temporal scales, new dynamic P-T-ε capabilities integrated with x-ray spectroscopic, diffraction, and optical probes need to be established.

The use of pulsed laser heating [1] allows very substantial reduction of the average laser power needed to reach a certain temperature, moreover much higher temperatures can be reached. Recently we developed a microsecond (µs) pulsed laser heating technique using an electrically modulated fiber laser [2]. Using time resolved spectro-radiometry (with a gated CCD detector) combined with finite element calculations and x-ray diffraction measurements [3] we find that for certain regimes the temperature remains steady for almost the entire pulse duration. Moreover, there are no substantial axial temperature gradients across the sample. This opens the possibility of performing a variety of measurements as a function of temperature in the time domain. Several examples of studies will be given.

I will report on laser-driven shocked states of materials precompressed in the diamond anvil cell as was pioneered by a Livermore group [4]. New results on D2 precompressed to at least 30 GPa will be presented. These experiments aim to determine the bonding state and the electronic properties of fluid hydrogen approaching the plasma transition in the megabar pressure range. I will also report on new developments of a broadband optical spectroscopy technique (BBOS), which utilizes a broadband continuum generation in a photonic crystal fiber (PCF). Our tests show that this light source is sufficiently bright to perform optical spectroscopy measurements even in the presence of a very strong thermal radiation and optical fluorescence (e.g. in compressed O₂). Moreover, this technique makes even single pulse measurements (e.g. concomitantly with laser driven shocks) feasible. The results on measurements of the optical spectra of oxygen in the fluid state will be presented. We are currently developing Coherent Anti-Stokes Raman spectroscopy (CARS) diagnostic using ultrashort (<40 fs) laser pulses [5]; the results of the first tests will be presented. Future plans include the implementation of interferometric techniques utilizing short and chirped pulses with fast light detectors (e.g. streak cameras) to probe materials undergoing laser driven shock [4] and pulsed laser heating [1].

I thank D. Allen Dalton, R. Stewart McWilliams, Michael R. Armstrong, Jonathan C. Crowhurst, and Vitali Prakapenka for critically contributing to this work.

References:

1. A.F. Goncharov, J.A. Montoya, N. Subramanian, V.V. Struzhkin, A. Kolesnikov, M. Somayazulu, and Russell J. Hemley; J. Synchrotron Rad. 16, 769 (2009)
2. A.F. Goncharov, J.C. Crowhurst, V.V. Struzhkin, and R.J. Hemley; Phys. Rev. Lett. 101, 095502 (2008)
3. A.F. Goncharov, V.B. Prakapenka, V.V. Struzhkin, I. Kantor, M.L. Rivers, and D.A. Dalton; Rev. Sci. Instrum, 81, 113902 (2010)
4. M.R. Armstrong, J.C. Crowhurst, S. Bastea, and J.M. Zaug; J. Appl. Phys. 108, 023511 (2010)
5. H. Kano and H. Hamaguchi; Appl. Phys. Lett. 85, 4298 (2004)

Dynamics of Crystallization and Melting under Pressure

Vitali Prakapenka
Advanced Photon Source

Detail knowledge of the fundamental processes of crystallization and melting of minerals at high pressures is one of the key factors in understanding the complexity of the Earth's interior, its heterogeneous structure and dynamics. Pressure effects on the mechanism of crystal growth, melting phenomena and structure of the multi-component phases constituting the terrestrial and giant planets can be effectively studied with state-of-the-art technologies available at 3rd generation synchrotrons. Recent developments in continues laser heating technique, including application of fiber lasers and flat top laser beam shaping optics, result in significant improvement of the quality of x-ray data collected in-situ at high pressure and temperature in the DAC [1]. Nevertheless, the maximal static temperatures and time, achievable in the laser heated DAC, suitable for reliable in-situ high pressure synchrotron experiments, are limited. Especially it is noticeable in the Mbar pressure range due to fundamentally thin pressure chamber and the lack of insulating layers between laser heated ultra thin sample and highly thermal conductive diamond anvils. Significantly improved conditions at higher temperatures of samples in the DAC, that is essential for direct studies of minerals at the core-mantle conditions, may be generated with pulse laser heating technique shown to be very effective in reaching stable temperatures above 4000 K [2].

At GSECARS (Sector 13, Advanced Photon Source, USA), we have developed the in-situ time-resolved synchrotron x-ray diffraction technique combined with pulse double-sided flat top laser heating system in the DAC [3]. A frequency-modulated laser beam with various pulse widths in the range of 1-100 microseconds was synchronized with x-ray detector, synchrotron bunches and temperature measuring spectrometer. Controlling delay time between gated x-ray detector and/or synchrotron bunches and laser pulse, e.g. probing samples at different temperatures, we was be able observed the clear shift of sharp x-ray diffraction lines due to thermal expansion of the laser heated samples at high pressures. Furthermore, we have detected diffuse x-ray scattering from molten materials in the pulse laser heated DAC that allows us precisely constrain the high pressure melting curve in the Mbar pressure range. Employing short (microseconds) laser pulses we effectively suppress the heating of the surrounded sample area significantly reducing processes of temperature induced diffusion and chemical reaction [4].

The dynamic x-ray probe is the ideal choice for real time applications in static and dynamic high pressure and temperature experiments for studying physical and chemical properties of materials in Mbar pressure range when combination of the time resolved synchrotron techniques including diffraction, emission, absorption and inelastic scattering with pulse laser heating and time resolved optical diagnostic methods could be accomplished.

References:

1. V.B. Prakapenka, A. Kubo, A. Kuznetsov, A. Laskin, O. Shkurikhin, P. Dera, M.L. Rivers, and S.R. Sutton; High Pressure Research 28, 3225 (2008)
2. A.F. Goncharov, J.A. Montoya, N. Subramanian, V.V. Struzhkin, A. Kolesnikov, M. Somayazulu, and R.J. Hemley; J. Synchrotron Rad. 16, 769 (2009)
3. A.F. Goncharov, V.B. Prakapenka, V.V. Struzhkin, I. Kantor, M.L. Rivers, and D.A. Dalton; Rev. Sci. Inst. 81, 113902 (2010)
4. V. Prakapenka, G. Shen, and L. Dubrovinsky; High Temperatures - High Pressures 35/36(2), 237 (2003)

Single Crystal X-ray Diffraction and IXS of Elements under Extreme Pressure

Malcolm McMahon
University of Edinburgh

High-pressure science was revolutionized in the mid 1990's by the unprecedented intensity of synchrotron radiation offered by third generation light sources (3GLSs) such as the ESRF, APS and SPring-8. The arrival of 4GLSs such as the LCLS in the US and XFEL in Europe, will offer beak brilliances some i billion times higher than those available at 3GLSs, and radiation that is both coherent and contained within very short (<100 fs) pulses. Such sources offer wholly new opportunities to extreme conditions science, allowing entirely new P-T regimes to be accessed and new areas of high-pressure science to be investigated.

In this presentation I will give some personal ideas on the new science that we will be able to conduct on single-crystal samples contained within diamond anvil cells. None of this science is currently possible at high pressures, but I hope it will be within the next 5 years.

Illuminating Earth's Core-mantle Boundary with Ultrabrilliant X-rays

Jennifer Jackson
California Institute of Technology

Earth's core-mantle boundary (CMB) layer spans up to ~350 km of Earth's lower mantle above its liquid outer core, corresponding to a proposed temperature and pressure range of ~3300 to 4300 K and 115 to 135 GPa¹. Intermittent detection of seismic reflections in the vicinity of this region suggests that the CMB layer is compositionally heterogeneous and/or represents different phase assemblages². Interaction of the CMB layer with the liquid outer core could further augment this heterogeneity. In this contribution, we will present recent static-compression measurements to 170 GPa obtained using high-energy resolution x-ray spectroscopic methods on phases thought to be present at Earth's CMB region³. Such measurements yield important information on the atomic-scale dynamics of the select species in the sample⁴ and in combination with dynamic modeling⁵ provide new insight to the processes that may be occurring under such extreme conditions. However, there still exist significant gaps in our understanding of material's behavior under such conditions. We will discuss the potential applications for an energy recovery linac (ERL) to transform our understanding of Earth's CMB region. ERLs have the potential to be an excellent source of coherent hard x-rays, producing an exceedingly small x-ray source size and divergence⁶. Under the extreme conditions of deep planetary interiors, little is known about dynamical processes that determine phase stability and transitions, chemical reactivity, diffusivity and transport. The ultrabrilliant characteristics of an ERL can allow us to make breakthroughs in these areas of high-pressure research and answer fundamental questions regarding boundary layers deep inside planets⁷.

References:

1. E.J. Garnero, and D.V. Helmberger; "A Very Slow Basal Layer Underlying Large-scale Low-velocity Anomalies in the Lower Mantle Beneath the Pacific: Evidence from core phases", Phys. Earth Planet. Inter., 91, 161-176, doi:10.1016/0031-9201(95)03039-Y (1995)
2. T. Lay, J. Hernlund, and B.A. Buffett; "Core-mantle Boundary Heat Flow", Nat. Geosci., 1, 25-32, doi:10.1038/ngeo.2007.44 (2008); I. Sidorin, M. Gurnis, and D.V. Helmberger; "Evidence for a Ubiquitous Seismic Discontinuity at the Base of the Mantle", Science, 286 (5443), 1326-1331, doi:10.1126/science.286.5443.1326 (1999)
3. T. Lay, J. Hernlund, and B.A. Buffett; "Core-mantle Boundary Heat Flow", Nat. Geosci., 1, 25-32, doi:10.1038/ngeo.2007.44 (2008); I. Sidorin, M. Gurnis, and D.V. Helmberger; "Evidence for a Ubiquitous Seismic Discontinuity at the Base of the Mantle", Science, 286 (5443), 1326-1331, doi:10.1126/science.286.5443.1326 (1999)
4. J.M. Jackson; "Synchrotron-based Spectroscopic Techniques: Mössbauer and high-resolution inelastic scattering", E. Boldyreva and P. Dera (eds.), High-Pressure Crystallography: From Fundamental Phenomena to Technological Applications, doi: 10.1007/978-90-481-9258_5 (2010); Springer Science; W. Sturhahn, and J.M. Jackson; "Geophysical Applications of Nuclear Resonant Scattering", in Ohtani, E., ed., Advances in High-Pressure Mineralogy: GSA Special Paper 421, 157-174, doi:10.1130/2007.2421(09) (2007)
5. D.J. Bower, J.K. Wicks, M. Gurnis, and J.M. Jackson; "A Geodynamic and Mineral Physics Model of a Solid-state Ultra-low Velocity Zone", Earth Planet. Sci. Lett., doi: 10.1016/j.epsl.2010.12035 (2011)
6. D. Bilderback, J.D. Brock, D.S. Dale, K.D. Finkelstein, M.A. Pfeifer, and S.M. Gruner; New J. Phys. 12, 035011, doi: 10.1088/1367-2630/12/3/035011 (2010)
7. C. Sotin, J.M. Jackson, and S. Seager; "Terrestrial Planet Interiors. Exoplanets", ed. S. Seager, University of Arizona Press - Space Science Series (2010)