Upcoming Seminar: Dr. Narayanan Theyencheri, ESRF, France Dec. 10th, 2020 10AM (PST) Title: Structure and Dynamics of Soft Matter Probed by X-ray Scattering Join Zoom Meeting https://lbnl.zoom.us/j/94581875312?pwd=R0xldHRsZktCZURIaldVRjdTQ2xSZz09Prof. Fivos Perakis, Stockholm University, Sweden Feb. 4th 9AM (PST) Title: Molecular Movies with X-ray Photon Correlation Spectroscopy "In this presentation, I will highlight research opportunities and challenges in probing structural dynamics of molecular systems using X-ray Photon Correlation Spectroscopy (XPCS). The development of new X-ray sources, such as 4th generation storage rings and X-ray free-electron lasers (XFELs), provides promising new insights into molecular motion. Employing XPCS at these sources allows to capture a very broad range of timescales and lengthscales, spanning from femtoseconds to minutes and atomic scales to the mesoscale. Here, I will discuss the scientific questions that can be addressed with these novel tools for two prominent examples: the dynamics of supercooled water [1,2] and proteins [3]. Finally, I will provide practical tips for designing and estimating feasibility of XPCS experiments as well as on detecting and mitigating radiation damage. [1] F. Perakis et al, PNAS 114, 8193-8198 (2017) [2] F. Perakis et al, Nature Comm. 9, 1917 (2018) [3] F. Perakis and C. Gutt, Phys. Chem. Chem. Phys., 22, 19443-19453 (2020)" Dr. Zhang Jiang, Argonne National Laboratory Feb. 16, 2021 1pm (PST) Title: TBA (coherent surface scattering imaging) Prof. Karl Ludwig, Boston University Feb. 19, 2021 11AM (PST) Title: Coherent X-ray Scattering Studies of Surface Growth and Patterning Processes "In collaboration with the Headrick group at the University of Vermont, we have been developing the use of X-ray
Photon Correlation Spectroscopy (XPCS) to investigate dynamics during surface growth and patterning processes. In
this talk, we will focus primarily on recent results from studies of self-organized Ar + ion beam nanopatterning of Si.
Broad beam low-energy ion bombardment of surfaces can lead to the self-organized formation of patterns including
nanodots, nanoscale ripples and nanoscale pits/holes, as well as to ultrasmoothening. Despite extensive study,
however, there is not yet a consensus on what drives these behaviors. We have used XPCS to measure the evolving
surface dynamics during the nanopatterning process. As with de Gennes narrowing in liquids, we observe longest
correlation times at length scales corresponding to the dominant structural motif of the system – here, the self-
organized ripple pattern. However, in contrast to the exponential relaxation of fluctuations in classic de Gennes
narrowing, the dynamic surface exhibits a wide range of behaviors as a function of length scale, with a compressed
exponential relaxation at lengths corresponding to the dominant structural motif. These behaviors are reproduced
in simulations of a nonlinear model describing the surface evolution. We suggest that the compressed exponential
behavior is due to the morphological persistence of the self-organized surface ripple patterns which form and evolve
during ion beam nanopatterning. In addition, we find that systematic speckle motion during the surface evolution
can be analyzed to determine spatial inhomogeneities in erosion rate and ripple velocity. This allows the direction
and speed of ripple motion to be measured in a real time experiment. This is a fundamental parameter predicted by
competing theories which has been difficult to measure by other experimental approaches.
This material is based on work partly supported at BU by the National Science Foundation (NSF) under Grant No.
DMR-1709380 and by the U.S. Department of Energy (DOE) Office of Science under Grant No. DE-SC0017802 (UVM).
P. Myint et al., arXiv: 2007.12253 (2020); arXiv: 2007.12294 (2020).
P. Myint et al., Phys. Rev. Lett. 126, 016101 (2021).
R. Headrick et al., Nature Communications 10, 2638 (2019).
M. Mokhtarzadeh et al., Phys. Rev. B 99, 165429 (2019).
J. Ulbrandt et al., Nature Physics 12, 794 (2016)." Prof. Christian Gutt, University of Siegen Mar. 15 (Monday), 2021 9AM (PST) Title TBA Gordon Research Conference - Learning from Nature to Transform Technology through Liquid Crystal Science, June 27-July 2, 2021 -------------------- Past seminar (5) Dr. Andrei Fluerasu, Brookhaven National Laboratory, New York May 26, 2020 Title: The Coherent Hard X-ray Scattering beamline at NSLS-II: watching the nanoscale dance of materials (4) Prof. Robert Leheny, Johns Hopkins University, Maryland May 7, 2020 Title: Connecting microscopic dynamics and rheology of soft materials with x-ray photon correlation spectroscopy (3) Dr. Marios Georgiadis, Stanford University Time: April 10, 2020 Title: X-ray scattering tensor tomography on biological materials: applications on collagen fibers in bone and myelinated axons in the brain (2) Dr. Emily Davison (Harvard University) Title: Light-induced shape memory via 3D printing of bond-exchangeable LCEs Time: April 1, 2020 (1) Dr. Song Sanghoon (LCLS,SLAC) Title: "Dynamic studying in condensed matter with hard X-ray free electron laser at LCLS" Time: Wednesday, December 11,2019. Past workshops Corie Ralston (LBNL), Paul Adams (LBNL), Michael Martin (ALS, LBNL), Chenhui Zhu (ALS, LBNL) & Daniela Ushizima (CRD LBNL & UCB) Workshop (Virtual) at ALS User Meeting, Friday, August 28 2020. 14. Bioimaging Innovation Forum (July 24, 2020) - Virtual Corie Ralston (MF, MBIB), Hans Bechtel, Michael Martin, Chenhui Zhu (ALS), Daniela Ushizima (CRD LBNL & UCB), Peter Zwart (CRD), Andrea Tallor (ALS) Eric Meshot, Jun Feng, Chenhui Zhu, Cheng Wang, Alastair MacDowell. 12. "CAMERA XPCS workshop", Berkeley, CA, Feb. 26-27, 2019 11. "Self-assembly, Nanomaterials, and X-ray Scattering", Oct. 3rd, 2018. ALS User Meeting 2018, Oct. 2-4, 2018, Berkeley, CA 10. GISAXS summer school, Experiments and data analysis, Sep. 17-18, Bayreuth, Germany 9. Soft Matter Dynamics at the Nano- to Meso-Scale Workshop, Oak Ridge National Laboratory, Sep 17-18, 2018 Workshops at 2017 ALS User Meeting Workshop at 2016 ALS user meeting 5. The Future of Materials Exploration: Intelligent synthesis, discovery, characterization, and optimization(Workshop at 2015 ALS user meeting) (Workshop at 2014 ALS user meeting) |
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