2016 Liquid Surface X-ray Scattering School: Data Analysis

X-ray surface scattering is the most powerful probe of near-atomic-level structure at liquid-vapor and liquid-liquid interfaces. Synchrotron X-ray sources throughout the world have specialized instruments available for the study of these interfaces. Since 2002, the ChemMatCARS facility at Sector 15 of the Advanced Photon Source near Chicago, IL, USA, has assisted general users in the study of liquid surfaces and interfaces to model processes of interest to physical, chemical, and biological scientists. ChemMatCARS recently sponsored its third School for Liquid Surface X-ray Scattering (LSXS 2016), held at the Advanced Photon Source (APS) at Argonne National Laboratory on May 12–13, 2016. Methods of data analysis were featured, providing students with the opportunity to fit data, analyze errors, and participate in virtual experiments. Techniques covered this year included X-ray reflectivity (XR), grazing incidence diffraction (GID), X-ray fluorescence near total reflection (XFNTR), and X-ray photon correlation spectroscopy (XPCS). This is the third year that the LSXS School has been held at APS, the first year being in 2007 and the second in 2012.     

Ksrs inaugurated in moscow

To foster scientific collaborations among the Advanced Photon Source (APS), the European Synchrotron Radiation Facility (ESRF), and the Super Photon Ring-8 GeV (SPring-8), the three facilities meet on a regular basis to hold technical discussions on accelerator and beamline topics and management and operational issues of common interest. The 2008 Three-Way Meeting (3WM) was held on March 18–19 at the APS with more than 20 representatives from each facility. Satellite workshops were also held on the topics of X-ray Optics, Nanoscience with X-rays, User Services, and Accelerator R&;D. The 3WM and satellite workshops served as platforms for presentations and discussions of new and exciting developments at the three synchrotron sources.     

APS/CNM Users Meeting: Celebrating the International Year of Light

The International Year of Light and Light-Based Technologies (IYL) is a global initiative, adopted by the United Nations, to highlight the importance of light and optics technologies, and synchrotron light sources are recognized as important tools in revealing the atomic and molecular details of the world around us. The 2015 joint Advanced Photon Source (APS)/Center for Nanoscale Materials (CNM) Users Meeting was held on May 11–14. This article reports on the APS portion of the meeting. Apropos to both the IYL and the twentieth anniversary of the first X-ray beam at the APS, research highlights were presented and opportunities for upgrading the performance of the APS were discussed.     

Second International Workshop on Ambient Pressure X-ray Photoelectron Spectroscopy

The Second International Workshop on Ambient Pressure X-ray Photoelectron Spectroscopy (APXPS) was held at Lawrence Berkeley National Laboratory (LBNL) in Berkeley, CA, from December 7–9, 2015. It brought together more than 100 participants from 17 countries. The workshop followed the inaugural meeting at the French synchrotron SOLEIL in December 2014, which was organized by François Rochet. The strong interest in these workshops reflects the growth of the APXPS community over the last decade, with instruments now operational at more than 12 synchrotrons around the world (see SRN, Vol. 27, No. 2, pp. 14–23 (2014)), and a steady increase in the number of laboratory instruments. APXPS has established itself as an important method for the investigation of surfaces and interfaces under in situ and operando conditions, including liquid/vapor and liquid/solid interfaces.     

“X-ray Echo Spectroscopy: Opportunities and Feasibility” Workshop

A two-day workshop on “X-ray Echo Spectroscopy: Opportunities and Feasibility” was held at the Advanced Photon Source (APS), Argonne National Laboratory, USA, September 9–10, 2016, attracting 42 attendees. The focus of the workshop was to explore the scientific potential and technical feasibility of the recently proposed X-ray echo spectroscopy and to discuss a path for its R&D and realization.     

Surface chemistry at the liquid/solid interface

In this Prospective, a critical overview is provided on the status and future of the analytical techniques available for the study of chemistry at liquid/solid interfaces. A number of spectroscopies already available are identified, including infrared absorption, surface-enhanced Raman (SERS) and sum frequency generation (SFG) to obtain vibrational information, and second harmonic generation (SHG) and X-ray absorption (XAS) to provide electronic details of surfaces and adsorbates. X-ray scattering and X-ray diffraction techniques are also used for structural characterization, and surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) to follow adsorption uptakes and kinetics. Finally, optical and scanning microscopies add a spatial dimension to these studies. Overall, a number of surface-sensitive techniques do already exist to address chemical issues at liquid/solid interfaces, but those are still limited, and have perhaps not been exploited to their fullest yet. There is also a need for more cross collaboration among different research communities, and for new and clever developments to augment the toolbox of liquid/solid interface characterization.     

News and Views: Major European Light Sources Join Forces in the ERF

Synchrotron-based X-ray scattering (SR-XRS) techniques offer the ability to probe nano- and atomic-scale structures that dictate the properties of advanced technological and environmental materials. Important materials studied at the Stanford Synchrotron Radiation Lightsource (SSRL) include organic and inorganic thin films and interfaces, nanoparticles, complex oxides, solutions, polymers, minerals, and poorly crystalline materials. Good planning and a good working knowledge of beamlines and techniques are required to successfully conduct SR-XRS measurements. This sixth annual School at SSRL on Synchrotron X-ray Scattering Techniques in Materials and Environmental Sciences was held at the SLAC National Accelerator Laboratory on May 29-31, 2012, and provided a practical users' guide to planning and conducting scattering measurements at SSRL beam lines. There was an emphasis on information that cannot be found in textbooks. More than 50 researchers, mostly graduate students and postdoctoral associates, participated in this workshop. Attendees represented a variety of fields including material sciences, chemical engineering, applied physics, chemistry and earth sciences.     

Fifteenth International Conference on X-ray Absorption Fine Structure

The 15th International Conference on X-ray Absorption Fine Structure (XAFS15) was held at the Pullman Beijing West Wanda Hotel in Beijing, China, on July 22–28, 2012. The conference was chaired by Ziyu Wu (Chinese Academy of Sciences). In conjunction with XAFS15, the workshop “XAFS theory and nano particles” was held July 18–20, 2012, in Chiba, Japan, and chaired by T. Fujikawa.     

Height and density correlations at liquid surfaces; application to X-ray scattering

We calculate height-height correlation functions, near-surface density-density correlation functions and the corresponding frequency integrated spectra for a heat conducting viscous fluid. We calculate scattering cross-sections for the static and dynamic X-ray scattering experiments recently developed to investigate the nanometer-scale structure and fluctuations of liquid interfaces. We show that the density-density correlations make an important contribution to the scattering, even using evanescent waves, and that they are strongly affected by the surface. We also discuss the implications for X-ray photon correlation spectroscopy and X-ray inelastic scattering. Received 12 October 2001 Published online 6 June 2002     

2011 U.S. National School on Neutron and X-ray Scattering

The 13^th annual U.S. National School on Neutron and X-ray Scattering was held June 11-25, 2011, at both Oak Ridge and Argonne National Laboratories. This school brought together 65 early career graduate students from 56 different universities in the United States and provided them with a broad introduction to the properties and techniques available at the major large-scale neutron and synchrotron X-ray facilities. This school is focused primarily on techniques relevant to the physical sciences, but also touches on cross-disciplinary bio-related scattering measurements. During the school, the students received lectures by more than 30 researchers from academia, industry, and national laboratories and participated in a number of short demonstration experiments at Argonne's Advanced Photon Source (APS) and Oak Ridge's Spallation Neutron Source (SNS) and High Flux Isotope Reactor (HFIR) facilities to get hands-on experience in using neutron and synchrotron sources.     

Infrared workshop held at the SRC

The 2005 Advanced Photon Source (APS) User Meeting commemorated the tenth anniversary of first light at the APS. The weeklong meeting, with more than 600 participants, was held May 2–5, 2005, in collaboration with the new Center for Nanoscale Materials (CNM). The CNM, sited adjacent to the APS experiment hall, is currently under construction. Monday's session concentrated on CNM activities. Business and science sessions on Wednesday and Thursday morning highlighted the APS. Nine workshops related to CNM and APS science filled the schedule on Tuesday, Thursday afternoon, and Friday.     

DMLS 2011: Fourth International Workshop on Diamonds for Modern Light Sources

The fourth in a series of workshops devoted to the use of diamonds at synchrotrons and free electron lasers (FELs) was held on May 5-6, 2011, at the Advanced Photon Source. The previous DMSL workshop was held in Japan in 2008. The workshop was supported in part by Argonne National Laboratory; Applied Diamond, Inc.; SINMAT, Inc.; and elementsix, Ltd. The scope was to assess : 1) the status, size, quality, and availability of synthetic type IIa diamonds; 2) the status of CVD diamonds; 3) applications for beamline optics; 4) applications for beam position monitors (BPMs) and detectors; 5) applications at FELs; and 6) novel applications, such as for an X-ray free electron laser oscillator (XFELO). On May 5, Linda Young (APS/XSD) gave the workshop welcome. There were three sessions on each of the two days. A website was created and will be kept live where the detailed age-nda and list of speakers will remain available (http://www.aps.anl.gov/News/Conferences/2011/DMLS). As part of the session on BPMs and detectors, there were several speakers from outside the light source community, which demonstrated that there is a larger science audience for these applications than just light sources. Highlights of the workshop include: 1) reports of supplier facilities for thinning and polishing; 2) reports on tests of supplier-provided bonds to CVD cooling manifolds; 3) a report of more than 99% reflectivity from diamond for hard X-rays, significant for XFELO feasibility, measured at the APS; 4) a report on thermal expansion measurements at low temperatures made at the APS (no negative thermal expansion, thermal expansion below 1e-9); 5) a report from Brookhaven National Laboratory on substantial progress in diamond beam flux monitors (BPMs), and fast detectors; 6) a presentation on plans for a self-seeding at LCLS with diamond crystals. A synopsis of each technical session follows below.     

International Henry Moseley School and Workshop on X-ray Science

Under the glowing southern Turkish sun, a group of 54 students from eight different countries and 18 teachers from all over the world gathered for 10 days to learn about and discuss the latest developments in the applications of X-rays in different branches of science. The International Henry Moseley School and Workshop on X-ray Science was held at the Institute of Theoretical and Applied Physics in Turunç, Turkey, from June 14 to 23, 2012.     

Molecular layering and local order in thin films of 1-alkyl-3-methylimidazolium ionic liquids using X-ray reflectivity

X-ray reflectivity measurements in air of thin films of 1-alkyl-3-methylimidazolium salts in the liquid, liquid crystalline and solid states supported on Si(111) are described. The films show Bragg features in both liquid crystalline and solid phases, but only after an initial annealing cycle. Kiessig fringes are observed only for the 1-octadecyl-3-methyl-imidazolium hexafluorophosphate films and, following analysis using Parratt32, a bi-layer model is proposed whereby the molecules are orientated with ionic groups at both salt-air and salt-silicon interfaces.     

Meeting Report: SSRL School on Synchrotron X-ray Scattering Techniques in Materials and Environmental Sciences: Theory and Application

Modern synchrotron-based X-ray scattering (SR-XRS) techniques offer the ability to probe nano- and atomic-scale structures, interfaces, and order/disorder relationships that govern the properties of advanced technological and environmental materials. Important materials studied at the Stanford Synchrotron Radiation Laboratory (SSRL) include thin films and interfaces, nanoparticles, amorphous materials, solutions, polymers, and bacteriogenic minerals. Good planning and a working knowledge of beam lines and techniques are required to successfully conduct SR-XRS measurements. This second annual School at SSRL on Synchrotron X-ray Scattering Techniques in Materials and Environmental Sciences, held at the Stanford Linear Accelerator Center (SLAC) on May 15–17, 2007, provided a practical users' guide to planning and conducting scattering measurements at SSRL beam lines, with an emphasis on information that cannot be found in textbooks. More than 45 researchers, mostly graduate students and postdocs, participated in this crosscutting workshop. Attendees represented a variety of fields including material sciences, applied physics, environmental sciences, and chemistry.     

A silane pre-treatment for improving corrosion resistance performances of emeraldine base-coated aluminium samples in neutral environment

An aluminium-magnesium alloy AA5182 substrate pre-treated with a 3-aminopropyl-triethoxysilane (APS)-based solution and coated with emeraldine base (EB) showed improved corrosion resistance to neutral salt spray test, compared to samples pre-treated with phosphoric acid-based solutions prior to the EB coating. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX) characterisations of samples pre-treated with APS showed the presence of an uneven silane coating on the aluminium surface according to the surface microstructure. The potentiodynamic study performed on the EB-coated samples showed a noticeable reduction of corrosion current of coupons pre-treated with APS, while no relevant difference in corrosion behaviour was observed between APS and phosphoric acid pre-treated samples prior to the EB coating. The coupling activity of APS between the AA5182 surface and EB coating at the most sensitive corrosion sites could be responsible of an improved adhesion of the EB coating at these points and could explain the observed improved corrosion resistance.     

Design and study of a high-current 5-cell superconducting rf cavity

The Advanced Photon Source （APS） at Argonne National Laboratory is considering the development of a superconducting linac-based fourth-generation hard X-ray source to meet future scientific needs of the hard X-ray user community. This work specifically focuses on the design of an optimized 5-cell superconducting radio-frequency structure well suited for a high-energy, high-beam-current energy recovery linac. The cavity design parameters are based on the APS storage ring nominal 7 GeV and 100 mA beam operation. A high-current 5-cell cw superconducting cavity operating at 1.4 GHz has been designed. In order to achieve a high current, the accelerating cavity shape has been optimized and large end-cell beam pipes have been adopted. The beam break-up threshold of the cavity has been estimated using the code TDBBU, which predicts a high threshold beam current for a 7 GeV energy recovery linac model. A copper prototype cavity has been fabricated that uses half-cell modules, initially assembled by clamping the cells together.     

Adsorption at liquid interfaces: A comparison of multiple experimental techniques

It has proven to be a challenging task to quantitatively resolve the interfacial profile at diffuse interfaces, such as, the adsorption profile near a bulk binary liquid mixture critical point. In this contribution we examine the advantages and disadvantages of a variety of experimental techniques for studying adsorption, including neutron reflectometry, X-ray reflectometry and ellipsometry. Short length scale interfacial features are best resolved using neutron/X-ray reflectometry, whereas, large length scale interfacial features are best resolved using ellipsometry, or in special circumstances, neutron reflectometry. The use of multiple techniques severely limits the shape of the adsorption profile that can describe all experimental data sets. Complex interfaces possessing surface features on many different length scales are therefore best studied using a combination of neutron/X-ray reflectometry and ellipsometry.     

Valence photoemission study of temperature dependent reaction products in Ni-Si interfaces and thin films

Si(lll)-Ni interfaces were prepared by deposition of Ni onto Si(lll) held at liquid nitrogen temperature (LNT) and successively heated. We give angle integrated photoemission results (hν=21.2 eV) at LNT and at room temperature as a function of coverage (up to 10 monolayers). We also give photoemission results for bulk Ni₂Si and NiSi prepared “in situ” by interdiffusion. The results are discussed in terms of the properties of the products formed in the interface reacted region.     

Improving Beamline X-ray Optics by Analyzing the Damage to Crystallographic Structure

The mission of the X-ray Characterization Laboratory in the X-ray Science Division (XSD) at the Advanced Photon Source (APS) is to support both the users and the Optics Fabrication Facility that produces high-performance optics for synchrotron X-ray beamlines. The Topography Test Unit (TTU) in the X-ray Lab has been successfully used to characterize diffracting crystals and test monochromators by quantifying residual surface stresses. This topographic method has also been adapted for testing standard X-ray mirrors, characterizing concave crystal optics and, in principle, can be used to visualize residual stresses on any optic made from single crystalline material.