We warmly invite you to participate in a new series of scientific seminars organised by the User Office at MAX IV, Lund University
Where – Virtual format by Zoom call https://lu-se.zoom.us/j/61349123545
When – Mondays 13:45 CET
Format – 30 minutes of presentation followed by 15 minutes of discussion, chaired by MAX IV staff
Monday 18 January 2021, 13:45 CET
Time-resolved SAXS studies of nanocube assembly in levitating drops
Speaker: Prof Lennart Bergström, Department of Materials and Environmental Chemistry, Stockholm University, Sweden
Host: Dr Tomás Plivelic, manager at CoSAXS beamline
Keywords: Nanoparticle assembly, Time-resolved small-angle X-ray scattering (SAXS)
Nanoparticle assembly is a promising route to produce mesostructured materials with unique properties. Probing the dynamics of assembling nanoparticles in liquids is challenging and requires not only methods with suitable spatial- and time-resolution, but also careful design of measurement environments. Here, recent work on time-resolved techniques has been used to probe nanocube assembly in levitating drops. Time-resolved small-angle X-ray scattering (SAXS) combined with electron microscopy and interparticle potential calculations showed that the evaporation-induced mesocrystallization process proceeds in two stages involving the formation and rapid transformation of a dense, structurally disordered phase into ordered mesocrystals (1). It will be demonstrated how evaporation-driven poor-solvent enrichment allows for the assembly of large particle assemblies, which display a higher crystalline quality compared to the classical single solvent approach (2). Evaporation-induced assembly in weak magnetic fields was found to proceed in two stages where assembly of micron-sized mesocrystals with a cubic shape preceded the formation of fibres with a high degree of crystallographic coherence and tunable diameters (3). We will discuss how the transition from 3D growth of the primary mesocrystals to the second stage 1D assembly of the elongated fibres was related to the size and field dependence of isotropic van der Waals and directional dipolar interactions between the interacting mesocrystals.
1.M Agthe, T S. Plivelic, A Labrador, L Bergström, G Salazar-Alvarez, Nano Lett., 16, 6838-6843 (2016)
2. Z-P Lv, M Kapuscinski, L Bergström, Nature Comm., 10, 4228 (2019)
3. M Kapuscinski, P Munier, M Segad, L Bergström, Nano Lett., 20, 10, 7359–7366 (2020)
Monday 25 January 2021, 13:45 CET
Semiconductor nanostructures for future devices: Studying surface chemistry in-situ
Speaker: Prof Rainer Timm, Department of Physics, Synchrotron Radiation Research, NanoLund, Lund University, Sweden
Host: Dr Andrey Shavorskiy, manager at HIPPIE beamline
Keywords: semiconductor nanostructures, ambient-pressure XPS
Semiconductor nanostructures made of III-V alloys such as InAs are promising for electrical devices with superior performance compared to Si technology. However, the quality of the interface to the semiconductor still limits the progress. Here, I will compare results from different MAX IV spectroscopy and imaging beamlines to investigate the interface between InAs substrates or nanowires and thin oxide or metal layers. The main focus will be placed on ambient-pressure XPS studies performed during the atomic layer deposition of a thin dielectric, which simultaneously removes the unwanted native oxide. By monitoring the surface chemistry during the ongoing reaction, we could reveal new insights in this industrially relevant process.
Monday 1 February 2021, 13:45 CET
Permanent magnets a challenge of size, shape, and orientation
Speaker: Prof Mogens Christensen, Department of Chemistry, Aarhus University, Denmark
Host: Dr Mads Ry Jørgensen, manager at DANMAX beamline
Keywords: magnetic materials, textured materials, X-ray and neutron diffraction, instrument development
Magnetic materials are omnipresent in our daily life’s, ranging from electromotors and generators converting between kinetic energy and electricity to hard drive data storage. Magnetism is a quantum mechanical phenomenon related to the number of unpaired electrons on the atomic level. Understanding and controlling structures from the atomic via the nanoscale to the microscopic level allows the design and building of better performing magnetic materials. Synchrotron light is essential for investigating the compaction and alignment of permanent magnetic material on a sub-second time scale. The obtained information will be utilized to improve the processes and enhance the performance of magnetic materials.
Monday 8 February 2021, 13:45 CET
Serial crystallography as a tool to study protein structure and dynamics
Speaker: Prof Gisela Brändén, Department of Chemistry & Molecular Biology, University of Gothenburg, Sweden
Host: BioMAX beamline
Keywords: serial crystallography, X-ray diffraction, protein structure and dynamics
Serial crystallography is a novel method within macromolecular crystallography that allows determination of protein structures at room temperature and enables time-resolved studies of protein dynamics. The method was first developed at X-ray free electron lasers, but has during the last few years been successfully established also at synchrotron facilities. For serial crystallography to become accessible to more users a number of challenges have to be overcome, especially regarding sample preparation, delivery and reaction triggering. Here, I will describe how we use serial crystallography to study challenging membrane proteins and biological targets of pharmaceutical interest. In await of the dedicated beamline MicroMAX, we have been involved in establishing the method at BioMAX through a series of experiments using various sample delivery setups.
Monday 15 February 2021, 13:45 CET
Speaker: Prof Jan-Erik Rubensson, Department of Physics and Astronomy, Molecular and Condensed Matter Physics, Uppsala University, Sweden
Host: Dr Victor Ekholm, scientist at the VERITAS beamline
Monday 22 February 2021, 13:45 CET
The study of GGAG scintillating crystals by means of UV-VUV luminescence excitation spectroscopy
Speaker: Dr Vladimir Pankratov, Institute of Solid State Physics, University of Latvia, Latvia
Host: Dr Antti Kiwimäki, manager at FinEstBeAMS beamline
Keywords: scintillators, luminescence, VUV excitation spectroscopy
Scintillator detectors play an irreplaceable role in high-energy physics, spectrometry of low energy γ- quanta, applications in medical imaging, safety systems, space applications, well and mud logging. Among other scintillators cerium doped gallium gadolinium aluminum garnet (Gd3Ga3Al2O12:Ce or GGAG:Ce) nowadays is one of the most relevant scintillator materials. Luminescence properties under UV-VUV excitation reveal the electronic structure of Ce3+ exited states and energy transfer process in the co-doped GGAG:Ce single crystals. The obtained information will be utilized to improve and modify growing technology and enhance the scintillation performance of GGAG single crystals.
The initiative aims to share knowledge and stimulate enthusiastic discussions on synchrotron research and methods developed at MAX IV. These shall be a channel to learn more about our facility, strengthen collaborations, bring communities together and promote cooperation and interdisciplinarity. The speakers will be MAX IV past, current and potential future users, as well as MAX IV staff; on the other hand, welcome attendees are members of the broad scientific community: scientists from the speaker´s home institution, of Swedish and international universities as well as MAX IV and other light sources staff.
We look forward to seeing you online and hope you enjoy the talks!