Michael Behr, The Dow Chemical Company
Shen Dillon, University of Illinois at Urbana-Champaign
Yuzi Liu, Argonne National Laboratory
Sang Ho Oh, Pohang University of Science and Technology
Symposium Support Argonne National Laboratory
Hitachi High Technologies America Inc.
JEOL USA, INC.
VV2: Nanomaterials Meet AFM
Monday PM, November 30, 2015
Sheraton, 2nd Floor, Constitution B
2:30 AM - *VV2.01
In-Situ Mapping of the Self-Assembly and Dynamics of Single Ions at the Surface of Minerals in Water
Kislon Voitchovsky 1 Maria Ricci 2 Peter Spijker 3
1Durham Univ Durham United Kingdom2EPFL Lausanne Switzerland3Aalto University Helsinki FinlandShow Abstract
The behaviour of water and ions at the interface with immersed solids plays a central role in processes such as crystal growth and dissolution and biomineralisation. Gaining insights into the molecular mechanism underlying these processes remains challenging, partly because of the need to probe the system in-situ, locally and with sub-nanometre resolution.
Atomic force microscopy (AFM) can in principle overcome these difficulties, with recent developments making it possible to map sub-nanometre details of the interfacial liquid  and gather quantitative information about its local dynamics [1-2]. Here AFM is used to create images of single metal ions close to the surface of minerals immersed in aqueous solutions [3-4]. The behaviour of the water molecules controls the organisation of ions at the interface and can considerably slow down their dynamics, depending on their hydration properties. Results obtained near surface singularities such as atomic steps, or adsorbed organics highlight the impact that these local perturbations have on the behaviour of the interfacial water and ions, with consequences for the fate of the mineral.
 Voitchovsky et al., Nat. Nanotechnol., 5, 401, (2010)
 Ortiz-Young et al., Nat. Commun., 4, 2482, (2013)
 Ricci et al., Langmuir, 29, 2207, (2013)
 Ricci et al., Nat. Commun., 5, 4400, (2014)
3:00 AM - VV2.02
An In Situ View of Direct and Two-Step Nucleation Dynamics
James J. De Yoreo 1 2 Xiang Ma 1 Michael H Nielsen 3 4 Chun-Long Chen 1 Shaul Aloni 4
1Pacific Northwest National Lab Richland United States2University of Washington Seattle United States3University of California Berkeley United States4Lawrence Berkeley National Laboratory Berkeley United StatesShow Abstract
In the classical picture of nucleation, density fluctuations that are inherent at finite temperature form unstable clusters of the new phase through monomer-by-monomer addition. Clusters transition from unstable to stable if they exceed a critical size, beyond which the free energy cost of creating the new phase boundary is compensated by the drop in chemical potential. In recent years, hierarchical pathways involving assembly of species more complex than monomers have been proposed for numerous systems. Amongst these pathways, a “two-step nucleation” process was proposed whereby macromolecular crystals nucleate within monomer-rich, non-crystalline clusters. However, reports of such pathways are almost entirely based on computational models or interpretations of indirect observations. Moreover, little is known about two-step nucleation dynamics, and whether the monomers in the clusters are one and the same as those that comprise the crystal nucleus or are act instead to provide an environment for heterogeneous nucleation is uncertain, as is the extent to which two-step pathways are general features of either macromolecular or inorganic materials. To address these knowledge gaps, we have used in situ TEM and AFM to investigate nucleation in numerous systems.
To examine nucleation pathways of macromolecules, we synthesized a biomimetic polymer sequence that forms 2D ordered structures and used in situ AFM to observe nucleation. Our results show that the nucleation occurs along a two-step pathway that begins with creation of disordered clusters containing ~ 10-20 molecules. These clusters transform directly into ordered nuclei that grow via molecule-by-molecule addition, with the kinetics of transformation strongly dependent on Ca concentration. However, when a small aggregation-promoting hydrophobic region is deleted, even though the same final structure is obtained, nucleation occurs in a single step and the kinetics are dramatically altered.
To investigate nucleation of simple inorganic materials, we used in situ TEM to observe nucleation of CaCO3. Formation pathways are confirmed in most cases by collecting diffraction information of the observed phases. We find that amorphous calcium carbonate (ACC), as well as the three predominant crystalline phases: calcite, vaterite, and aragonite, can form directly even under conditions in which ACC readily forms. In addition to these direct formation pathways, we observe two-step nucleation of aragonite and vaterite from ACC. Here, ACC transforms directly to the crystalline phases through distinct nucleation events on or just beneath the surface followed by consumption of the parent ACC particle.
The results demonstrate that two-step pathways are possible in both inorganic and macromolecular systems, but are not universal. They can be accompanied by direct nucleation pathways and, in the case of macromolecules, their existence can depend on the specific sequence of the molecule.
3:15 AM - VV2.03
In Situ Atomic Force Microscopy Reveals Adsorbates on the Mica Surface as Potential Precursors to the Heterogeneous Nucleation of Rubidium Iodide
Benjamin A Legg 1 James J. De Yoreo 1
1Pacific Northwest National Lab Richland United StatesShow Abstract
In recent years, significant efforts have been mounted to directly image and quantify the population subcritical nucleation clusters that participate in crystal nucleation from solution. Such an achievement would provide great insight into the energy landscape for nucleation of new particles. However, the critical structures involved in nucleation are typically either too small or too scarce to be unambiguously detected using techniques such as in situ electron microscopy or X-ray scattering. However, recent advances in atomic force microscopy have demonstrated the ability to image in fluid with true atomic resolution, including the adsorption of single ions on atomically flat surface such as mica. We will report on efforts to directly image adsorbate structures on atomically flat surfaces, with interest in these adsorbates as precursors to heterogeneous nucleation. Our work focuses on alkali halide solutions, which are known to form epitaxial crystals on mica surfaces. We have developed an approach by which rubidium iodide crystal nucleation can be induced and observed in-situ with optical microscopy, and the site of nucleation can be investigated in detail with AFM. Unsurprisingly, nucleation is often found to occur at preexisting structural defects. Furthermore, our efforts to investigate the process of nucleation with atomic resolution have indicated the frequent occurrence of nanometer-scale surface heterogeneities. When sufficiently soft imaging forces are used (i.e. subnanometer tip oscillation amplitudes), we can observe the formation of adsorbate islands with thicknesses on the order of several angstroms, even in subsaturated salt solutions. These islands appear to coarsen slowly over time, and can be removed with sufficiently aggressive imaging forces.
VV3: Dynamic Processes and Materials Transformations Observed In Situ
Monday PM, November 30, 2015
Sheraton, 2nd Floor, Constitution B
4:00 AM - *VV3.01
Ultrafast/Nanoscale Dynamic Study by X-Ray Microscopy
Jung Ho Je 1 Ji San Lee 1 Su Ji Park 2 Byung Mook Weon 3
1POSTECH Pohang Korea (the Republic of)2Korea Atomic Energy Research Institute Daejeon Korea (the Republic of)3Sungkyunkwan University Suwon Korea (the Republic of)Show Abstract
Phase contrast x-ray microscopy, which is appropriate in dynamic studies at extreme conditions of high spatial (~ nm) and/or temporal (~mu;s) resolutions in bulk systems, was applied to ultrafast and nanoscale dynamic studies of ‘drop impact&’ and ‘wetting&’, respectively. In a drop impact on a solid surface, we directly visualized the profile of an entrapped air film and its evolution into a bubble during drop impact, using ultrafast (~mu;s) x-ray microscopy, and identified the complicated evolution process of the air into a bubble . Using ultrafast x-ray microscopy in drop impact, we also investigated the dynamics of bubble bursting at an air-liquid interface and identified the jetting mechanism during bubble bursting . Our results demonstrate that jetting in bubble bursting is analogous to pinching-off in liquid coalescence. Finally, we applied nano-resolution (~ 30 nm) X-ray microscopy to study wetting on soft solids . We directly visualized wetting ridges with a high spatio-temporal resolution and revealed a universal wetting principle from the tip geometry of ‘wetting ridges&’. On-going dynamic studies of vortex formation and wetting-ridge dynamics using ultrafast and nanoscale X-ray microscopy will be shortly introduced.
 J.S. Lee et al, Phys. Rev. Lett, 109, 204501 (2012).
 J.S. Lee et al, Nat. Comm.2, 367 (2011).
 S.J. Park et al, Nat. Comm., 5, 4369 (2014)
4:30 AM - VV3.02
3D Structure Study of Individual Nanocrystals in Solution
Jungwon Park 1 Hans Elmlund 3 Peter Ercius 2 David Weitz 1 A. Paul Alivisatos 4
1Harvard University Cambridge United States2The Molecular Foundry Berkeley United States3Monash University Clayton Australia4Lawrence Berkeley National Laboratory Berkeley United StatesShow Abstract
We introduce a new reconstruction method, 3D SINGLE (Structural Identification of Nanocrystals by Graphele Liquid cell Electron microscopy), for identifying 3D atomic structures of individual heterogeneous nanoparticles in their native solution. The combination of techniques from the soft and hard matter sciences, high-resolution graphene liquid cell electron microscopy, new direct electron detection technology, and algorithm for ab initio single-particle 3D reconstruction, is applied to separately reconstruct 3D structure of individual Pt nanocrystals freely-moving in the solution at atomic-scale. Particle by particle 3D reconstruction discloses the heterogeneous structural nature of individual Pt nanocrystals grown in a solution.
4:45 AM - VV3.03
In situ 3D X-Ray Imaging Technique for Deforming and Moving Micro-Objects
Hyeonjeong Cho 1 Namseop Kwon 1 Jung Ho Je 1 Akira Tsuda 2
1Pohang University of Science and Technology(POSTECH) Pohang Korea (the Republic of)2Harvard University, School of Public Health Boston United StatesShow Abstract
In situ three-dimensional (3D) imaging of deforming as well as moving micro-objects is highly important to better understand dynamic study of organic or biological materials. For deforming micro-objects, it is feasible to perform in situ 3D imaging if the microtomographic speed can be much faster than the deformation rate. For deforming and moving micro-objects, however, it is a challenge to in-situ image micro-objects in 3D. Pulmonary alveoli that inflate (deflate) and simultaneously move significantly in inspiration (expiration) are a typical example of deforming and moving micro-objects. In situ 3D imaging of pulmonary alveoli in live animals has been therefore hampered mostly by this active lung movement in respiration. Recently, we developed a tracking X-ray microscopy that enables us to perform in situ microtomography of alveoli during 180° rotation of a live mouse in respiration, based on inspiratory and expiratory triggering . However, automatic segmentation, an essential step toward 3D volume-rendering, which is a challenging task for deforming and moving micro-objects, has yet to be developed. Here, we complete in situ 3D X-ray imaging of inflating (deflating) and moving alveoli in respiration by developing an automatic segmentation algorithm. An unavoidable critical issue in microtomography of deforming and moving micro-objects is the image-blurring problem. The key idea to resolve this issue is based on a self-developed binary image processing algorithm that applies iteration operators containing a series of pre-processed reconstruction images. From in situ 3D image data of alveoli, we identify each acinar unit with ducts and alveoli in live mice and analyze alveolar dynamics (geometry and expansion rate) during respiration. This analysis in alveolar dynamics would be significant for better understanding the mechanisms leading to alveolar- damage, for instance, during ventilator induced lung injury (VILI) commonly occurring in patients treated for acute respiratory distress syndrome (ARDS). We believe that our in situ 3D X-ray imaging technique can be applied to various 3D dynamics studies involving deforming and moving micro-objects.
 S. Chang, N. Kwon, B.M. Weon, J. Kim, C.K. Rhee, H. S. Choi, Y. Kohmura, M. Yamamoto, T. Ishikawa, and J. H. Je, Scientific Reports 3 (2013) 1304.
5:00 AM - VV3.04
Watching the Self-Assembly of Carbon Nanotube Films Using High-Speed In Situ X-Ray Scattering
Eric R Meshot 1 A. John Hart 2
1Lawrence Livermore National Lab Livermore United States2MIT Cambridge United StatesShow Abstract
The production of high-performance carbon nanotube (CNT) materials demands understanding of the growth behavior of individual CNTs as well as collective effects. We aim to understand the cooperative mechanisms and kinetics of CNT self-organization and how this may limit density and alignment in vertically aligned CNT “forests”. We use synchrotron radiation in combination with a high-frame-rate (100 Hz) pixel array detector to uniquely study in situ the intrinsically rapid processes during nucleation and self-organization of CNT films made by chemical vapor deposition. We calculate an order parameter from time-resolved, grazing-incidence small-angle X-ray scattering (GISAXS) images in order to quantify the evolution of CNT morphology as a function of growth time. Further, we elucidate the mechanisms of CNT self-organization by correlating the order parameter with real-time film height kinetics and qualitative CNT density measurements (from X-ray scattering intensity). We study a set of canonical CNT growth experiments (various thermal and chemical conditions) using a bilayer Fe/Al2O3 catalyst thin film on a Si wafer with C2H4/H2 precursors near atmospheric pressure and high temperatures (up to 825 deg C). Our results show that the kinetics of CNT self-organization are proportional to the vertical growth rate of the forest. This suggests that the disorder-order transition is the result of excluded volume interactions, which are in part governed by the lengthening rate of constituent CNTs, in conjunction with increasing number density of CNTs. We draw analogies with the isotropic-nematic (aligned) phase changes previously observed in CNT solutions and liquid crystals. Further, the beginning of upward forest growth marks the onset of vertical self-alignment, which occurs as the order parameter begins to saturate with time. However, both the final value of the order parameter and the kinetcs depend on processing conditions (e.g., catalyst annealing gases, temperature), indicating that inherent limits to the straightness (and thus defects) of the CNTs are linked to the nucleation conditions.  E. R. Meshot, E. Verploegen, M. Bedewy, S. Tawfick, A. R. Woll, K. S. Green, M. Hromalik, L. J. Koerner, H. T. Philipp, M. W. Tate, S. M. Gruner, A. J. Hart, ACS Nano 2012.  L. Onsager, Annals of the New York Academy of Sciences 1949, 51, 627-659.
5:15 AM - VV3.05
In-Situ Study of Nano-Ceria Synthesis by X-Ray Diffraction, Small Angle X-Ray Scattering and Pair Distribution Function Methods on a Laboratory Diffractometer
Michael E Hawkridge 1 Olga Narygina 2 Marco Sommariva 2 Nicholas Norberg 2 Milen Gateshki 2
1PANalytical Westborough United States2PANalytical B.V. Almelo NetherlandsShow Abstract
Understanding the synthesis process of any nano-material, including ceria, is a key point for the tailoring of properties and scaling for production. Here, we present the in-situ study of hydrothermal synthesis of nano-ceria by a combination of several x-ray scattering techniques on a laboratory diffractometer; X-ray diffraction (XRD) and small angle x-ray scattering (SAXS) are used to provide information about the crystal structure, crystallite size and particle size. Pair distribution function (PDF) analysis is used to provide information on the atomic ordering at various length scales. Combining these techniques, we are able to demonstrate that the lattice parameter, crystallite size and particle size of the nano-ceria all increase during the initial stages of growth. After a certain period, the lattice parameter stabilizes while the crystallite and particle size continue to increase at a diminished rate. In addition, we observe that the particles are formed from more than one crystallite, as the particle size is always greater than the crystallite size. Particular attention shall be given to the PDF results, as this technique is not typically associated with in-situ studies on laboratory diffractometers.
Cerium dioxide has numerous applications including use as a catalyst for petroleum refining, as a polishing agent, in coatings and as an electrolyte material for intermediate temperature solid oxide fuel cell. Although yttria stabilized zirconia is still the preferred electrolyte material, cerium dioxide offers an alternative, enabling operation at lower temperatures (500-600 °C). The ionic conductivity of ceria is approximately an order of magnitude greater than that of yttria stabilized zirconia for comparable doping conditions, especially if it is nano-crystalline. An additional advantage of nano-crystalline ceria is the lower sintering temperature due to the high surface energy of the nanoparticles.
5:30 AM - VV3.06
Dynamic Atom-Resolved Imaging of Pressure-Depended Morphology Transformation in PdCu Nanocrystals
Ying Jiang 1 Yong Wang 1 Ze Zhang 1
1Zhejiang University Hangzhou ChinaShow Abstract
Morphological transformations of nanocrystals in response to the heating and gas environments are crucial to understand heterogeneous catalysis. Although a myriad of progresses have been made in the past, large pressure gap still poses since most conditions nanocrystals encountered in previous work were far removed from the realistic catalytic reactions. Here, we controllably expose PdCu nanocrystals to H2 at pressures from 0.1 mbar to 1 bar above in a gas reactor. In situ atom-resolved transmission electron microscopy (TEM) studies reveal that when heating to 300 #730;C, the as-synthesized spherical PdCu nanocrystals preferentially transform into edge-truncated cubes with sharp facets, which is not observed in the low-pressure environment. Our work suggests the great influence of pressures on the nanocatalysts and proves the significance of the study on nanocrystal behaviors at realistic conditions.
5:45 AM - VV3.07
Watching the Growth and Coarsening of Si Particles in a Liquid: Insights from Four-Dimensional X-Ray Tomography
Ashwin J Shahani 1 Xianghui Xiao 2 Peter W. Voorhees 1
1Northwestern Univ Evanston United States2Argonne National Laboratory Lemont United StatesShow Abstract
Among the commercial aluminum alloy castings, hypereutectic Al-Si and Al-Si-Cu alloys are the most commonly used owing to their excellent hardness, corrosion resistance, and machinability. These properties depend strongly on the characteristics of the microstructure, e.g., the size, shape, and distribution of the highly anisotropic Si particles. The mechanisms controlling the growth and coarsening behavior of such particles above the eutectic temperature, which are critical to the semi-solid processing of the alloy, have been difficult to determine due to the lack of real-time experiments that can capture the 3D morphology of the particles. Thus, we probe the microstructural evolution of primary Si particles in an Al-32wt%Si-15wt%Cu alloy via in situ synchrotron#8209;based X-ray tomography. In order to assess the extraordinary morphological and topological complexity of the Si particles, we calculate curvatures, orientations, and velocities from the 4D (time and space resolved) data and track their evolution during the phase transformation. The results indicate that at long times, growth and coarsening are both diffusion-limited, despite the highly anisotropic particle morphology. This trend can be rationalized by postulating that twin defects provide the kink sites necessary for interfacial propagation. Other insights into the mechanisms responsible for the evolution of these complex systems that are attainable only through in situ 3D experiments will be given.
VV4: Poster Session I: In Situ Characterization I
Monday PM, November 30, 2015
Hynes, Level 1, Hall B
9:00 AM - VV4.01
An Observation of Nanostructural Pt Growth in Amphiphilic Block Copolymer Solutions with In Situ Liquid Cell TEM
Xin Chen 1 2 Xing Kong