We are very thankful to all our speakers for participating in the SCIENTÍFika series and sharing their experience with us, we hope to meet you on site very soon!

 

Monday 24 January 2022, 13:45 CET
Time-resolved and event-averaged
ambient pressure x-ray photoelectron spectroscopy

Speaker: Dr Jan Knudsen, MAX IV, Lund University

Host: Dr Andrey Shavorskiy, manager at HIPPIE beamline

Ambient pressure x-ray photoelectron spectroscopy (APXPS) is an excellent in-situ characterization technique for catalytic active surfaces as it is able to characterize the surface, adsorbates, and the gas-phase just above the surface simultaneously and while a chemical reaction is running. Unfortunately, the technique is slow with seconds or minutes of acquisition time per spectrum. This limits its use to identifying the equilibrium and majority phases present while the catalyst is active and makes the time domain inaccessible excluding for example studies of kinetic processes.

In this talk, we will demonstrate how this limitation can be overcome by the construction of event-averaged data from stroboscopic APXPS data acquired in a cyclic reaction environment [1]. Using a transient gas supply with rapidly changing composition, we will show how one can force a surface to oscillate between active and inactive phases using CO oxidation and Pd(100) as model reaction and surface, respectively. Ultimately, I will demonstrate that one can record spectra with 60 ms time resolution with an efficient acquisition time of 30 s by averaging over more than 500 events. The scientific case stories in my talk will include examples both acquired in mbar pressures at the HIPPIE beamline, MAX IV, and at ~100 mbar at the new POLARIS instrument, DESY.

As an outlook of my talk I will discuss temperature pulses, ultra-fast pump-probe experiments using gas composition pulses, and in general where event-averaged and time-resolved APXPS and the methodology applied to other synchrotron based techniques can take us in the future.

 

Monday 17 January 2022, 13:45 CET
Using Synchrotron XPS at low and high pressures to study the reaction mechanism of Fischer-Tropsch Synthesis on Cobalt Catalysts

Speaker: Dr Kees Jan Weststrate, Deputy Director of Syngaschem BV, The Netherlands

Host: Dr Andrey Shavorskiy, manager at HIPPIE beamline

Keywords: catalysis, surface sensitive analysis, Fischer-Tropsch synthesis,  XPS

Catalysis plays a crucial role in the chemical industry and it is an important topic in fundamental research. In heterogeneous catalysis the reactants bind to the surface of the catalyst where they react and form the desired product. All the action takes place in the outermost atomic layer of the catalyst material and surface sensitive analysis tools are needed to better understand how catalysts work. In my lecture I will discuss how synchrotron XPS can be used as a powerful surface analysis technique tool to obtain fundamental insights into the reaction mechanism of Fischer-Tropsch synthesis (FTS) on cobalt catalysts. This is an important reaction in which metallic cobalt nanoparticles catalyse the conversion of carbon monoxide and hydrogen (synthesis gas) into long hydrocarbon chains. This process is expected to play an important role in the future, since synthesis gas can be produced from renewable feedstocks. FTS can then be used to produce sustainable fuels and chemicals.

 

Monday 13 December 2021, 13:45 CET
Ultrafast interatomic processes investigated by electron-photon coincidence spectroscopy

Speaker: Dr Andreas Hans, Leading scientist, Experimental Physics, University of Kassel, Germany
Host: Dr Noelle Walsh, scientist at FlexPES beamline

Keywords: charge and energy transfer mechanisms, radiation biology, optical photons in multi-electron coincidence spectroscopy

The investigation of prototypical atomic and molecular clusters is an important step towards understanding the response of real-life matter to the exposure to ionizing radiation. Ever since the prediction of interatomic Coulombic decay (ICD) in 1997, a family of interatomic and intermolecular charge and energy transfer mechanisms has been identified to act in weakly bound matter upon VUV or X-ray photoionization. Their role in radiation biology and other fields is lively debated. I will report on recent progress and future perspectives in tracking and characterizing such processes by including optical photons in multi-electron coincidence spectroscopy.

 

Monday 6 December 2021, 13:45 CET
The VerSoX beamline: Near-ambient pressure XPS/NEXAFS at Diamond Light Source

Speaker: Dr Georg Held, Principal Beamline Scientist for B07(VERSOX), Diamond Light Source, UK
Host: Dr Andrey Shavorskiy, manager at HIPPIE beamline

Keywords: catalysts in ambient-pressure conditions

The near-ambient-pressure beamline B07 (Versatile Soft X-ray beamline) at Diamond Light Source opened for users in July 2017. It features two branch lines with endstations covering the pressure range from UHV to atmosphere. The energy range 50/170 – 2200/2800 eV allows accessing a wide range of core levels and is optimised for the electron kinetic energy range necessary to penetrate gas environments in the 10 mbar range. The differentially pumped beamline entrance and analyser of the NAP endstation enable measurements routinely up to 30 mbar. A small NEXAFS endstation is separated from the beamline by a window and allows pressures up to 1 bar. The talk will discuss the beamline designs and performance and present results of experiments studying industrial and model catalysts in ambient-pressure conditions, demonstrating the research possibilities it offers.

 

Monday 29 November 2021, 13:45 CET
IR spectromicroscopy and imaging with six decades of dynamic range

Speaker: Dr Ferenc Borondics, SMIS Beamline Manager, SOLEIL, France
Host: Dr Karina Thånell, manager at SoftiMAX beamline

Watch the video of the talk here.

Keywords: Synchrotron infrared spectromicroscopy, photothermal spectromicroscopy, vibrational properties and low energy electrodynamics of materials

Infrared spectroscopy has been in scientists’ toolbox for more than a century to obtain information about vibrational properties and low energy electrodynamics of materials. The beginning of the 80s brought the first commercial infrared microscopes to look into fine details. Far-field infrared spectromicroscopy had been pushed to its limits in the 90s at synchrotron facilities by exploiting the unrivaled quality of synchrotron radiation, i.e., low angular divergence and extremely high bandwidth. Synchrotron infrared spectromicroscopy beamlines provide diffraction-limited spatial resolution covering the whole IR range and enable experiments impossible otherwise. Later, the implementation of two-dimensional IR detectors allowed hyperspectral imaging of large samples with high spatial resolution. The turn of the century brought the advent of near-field IR techniques breaking through the diffraction limit. Combining high-brightness IR sources with atomic force microscopes to detect photothermal expansion or near-field scattering allows measurements hundreds of times below the diffraction limit reaching as high as ten-nanometer spatial resolution. Optically sampled photothermal spectromicroscopy has recently become available to bridge the resolution gap between the nanometer and micrometer range. We combine these techniques at the SMIS beamline to enable six orders of magnitude spatial dynamic range in infrared spectromicroscopy and support scientific discovery by exploiting the synchrotron source through commercial and custom instrumentation. In this talk, I will highlight discoveries made by SMIS staff and users enabled by the beamline’s capability and comment on the benefits of emerging, alternative sources.

 

Monday 15 November 2021, 13:45 CET
Correlated electrons and new temperature scales at the surfaces of 4f materials

Speaker: Dr Denis V. Vyalikh, Research Professor at Donostia International Physics Center (DIPC), Spain
Host: Dr Craig Polley, manager at BLOCH beamline

Keywords: rare-earth based compounds, novel f– driven phenomena, Rashba spin-orbit coupling, Kondo and exchange magnetic interactions

At the heart of strongly-correlated electron systems are the rare-earth based compounds, which traditionally attract considerable attention due to their exotic bulk properties. The surfaces of such materials, however, often do not receive the same attention as their bulk. However, it is reasonable to anticipate that the f– driven physics at the surface can be even much richer and more compelling than in the bulk. Lack of inversion symmetry and spin-orbit coupling, appearance of surface-electron states and resonances, relaxation and reconstruction, as well as strong changes of the crystal-electric field near and at the surface are the driving forces for novel f– driven phenomena, phases and temperature scales that are in remarkable difference to those in the bulk. On example of the RET2Si2 family materials, the bright examples of novel f-driven phenomena at the surfaces will be presented, which are defined by combinations of Rashba spin-orbit coupling, Kondo and exchange magnetic interactions.

 

Monday 1 November 2021, 13:45 CET
Chemical bonding of termination species in 2D carbides investigated through valence band UPS/XPS of Ti3C2Tx MXene

Speaker: Dr Lars-Åke Näslund, Senior Research Engineer, Department of Physics, Chemistry and Biology (IFM), Linköping University, Sweden
Host: Dr Esko Kokkonen, manager at SPECIES beamline

Keywords: two-dimensional materials, bonding and coordination of the termination species, Ultraviolet and X-ray Photoelectron Spectroscopy (UPS/XPS) and Resonant Photoemission Spectroscopy (resPES)

MXenes are a novel class of two-dimensional materials offering properties that may be useful in many different applications such as composite materials with high strength, fuel- and solar cells, 2D-based electronics, and energy storage systems. These properties are to a large extent determined by how termination atoms are arranged on the surface of the two-dimensional sheet, which also makes MXenes highly customisable. Useful techniques to study the bonding and coordination of the termination species are Ultraviolet and X-ray Photoelectron Spectroscopy (UPS/XPS) and Resonant Photoemission Spectroscopy (resPES).The valence band UPS/XPS spectra of the MXene material Ti3C2Tx show several separated features in the binding energy region 0-16 eV that are dominated by contributions from the Ti 3p molecular orbitals. Close to the Fermi level (Ef) the Ti 3p is mixed with Ti 3d and around 3 eV below Ef we can find the Ti 3p – C 2p hybridization. The valence band feature around 5 eV binding energy is dominated by Ti 3p – O 2p hybridization and around 8.6 eV binding energy we have a clear Ti 3p – F 2p feature. Resonant photoemission spectroscopy shows that the direct Ti 3d photoelectron process coincides with a participant autoionization process, which shows that the Ti 3d is mixed into the Ti 3p orbitals near Ef, into the Ti 3p – C 2p hybridization, and into the Ti 3p – O 2p hybridization but not into the Ti 3p – F 2p hybridization. Computed valence band UPS/XPS spectra show that the feature originating from O on the fcc-site is superposed on the feature from O on the bridge site between two surface Ti atoms. Furthermore, the computed valence band UPS/XPS spectra show that OH as termination species would add additional features with significant intensity in the binding energy region of 8-14 eV below Ef, which the experimentally recorded valence band UPS/XPS spectra do not display. The assumption of OH as a termination species is thus refuted. A feature at 7.2 eV in the valence band XPS spectra obtained using higher photon energies suggest that also Ti 4p states are involved in the bonding between Ti and O on the fcc-site.

 

Monday 18 October 2021, 13:45 CET
Molecular dissociation following x-ray absorption – how can we know, what happened during the crucial early stages

Speaker: Prof Edwin Kukk, Head of Materials Research Laboratory, University of Turku, Finland
Host: Dr Antti Kivimäki, manager at FinEstBeAMS beamline

Keywords: organic and biomolecules, X-ray absorption, molecular dissociation

X-ray ionization of organic and biomolecules is a process that is both of fundamental interest and of practical relevance for example in cancer treatment. The molecule is usually destroyed after x-ray absorption, but the mechanisms and factors that determine the eventual outcome of the dissociation – the fragment patterns and energies – is far from fully understood. Advanced spectroscopic techniques such as momentum imaging ion mass spectroscopy and various coincidence measurements, performed at synchrotrons and free electron lasers have greatly advanced our knowledge in this area. Particularly the femtosecond-scale pump-probe experiments have recently provided rare insights into the first tens and hundreds of femtoseconds following the photoionization.

We present examples on such studies at the SACLA free electron laser and at the recently commissioned Gas Phase Endstation of FinEstBeams beamline at MAX IV. They demonstrate that these two types of x-ray sources are complementary and their combined use helps to form a much more complete understanding of the complex quantum mechanical processes in the early stages of the x-ray induced molecular dissociation. In particular, recent MAX-lab results on the photodissociation of tetrabromothiophene and di-iodothiophene are presented, and it is discussed how synchrotron radiation, even though not inherently offering femtosecond-scale time-resolved capabilities, nevertheless provides very valuable clues on the early molecular dynamics.

 

Monday 11 October 2021, 13:45 CET
Direct visualisation of nano-particle aggregation and retention inside porous media

Speaker: Dr Henning Osholm Sørensen, Senior Researcher, Department of Physics, Technical University of Denmark
Host: Dr Innokenty Kantor, manager at DANMAX beamline

Keywords: X-ray tomography, nanoparticles, porous media, environmental remediation

Engineered nanoparticles are increasingly being used for different applications. Over time they will be released into the environment. Some of the engineered nanoparticles are developed and introduced into the environment on purpose in order to perform e.g. remediation of soils contaminated by chlorinated organic compounds. Whether realised consciously  or unintentionally introduced to the environment they can constitute an environmental risk. Therefore, we need to understand, and in turn be able to predict, the fate of the nanoparticles hereunder how they are transported and retained in porous media. Currently, very little is known about the basic processes involved in retaining nanoparticles during transport in porous media. We have, recently, started to study these processes that occur when injecting sulfidised zerovalent iron nanoparticles (S-nZVI) into porous media. We image the nanoparticles retained in porous sands directly at various stages and under different injection conditions. Here, we will present the first results showing the feasibility of studying nanoparticle retention mechanisms in porous materials using X-ray tomography and some outline some future ideas of using DanMAX at MAX-IV to perform in situ 3D imaging at different scales.

 

Monday 4 October 2021, 13:45 CET
Joint x-ray and neutron crystallography: similarities and differences between these complementary techniques

Speaker: Dr Suzanne Zoë Fisher, Group Leader Deuteration and Macromolecular Crystallization (DEMAX) Platform, European Spallation Source ERIC, Sweden
Host: Ana González, manager at BioMAX beamline

Keywords: Neutrons and X-rays, protein structures, single crystal Bragg diffraction

Neutrons and X-rays are complementary and powerful probes for the study of complex protein structures – from looking at active site residue geometry and electrostatics to understanding the atomic details of ligand binding. While the methods are complementary and based on the same principle (i.e. single crystal Bragg diffraction) the realities and practicalities of making it all work together are very different. In this talk I will explain the workflow and timelines typically involved – from sample needs, data collection possibilities, to flexible beamline support. It is not widely known that a key part of solving and interpreting neutron protein crystal structures is the availability of x-ray diffraction data for the same system/crystal. Putting all the pieces together to enable the user to obtain a high quality and meaningful structure remains a challenge. There can be quite a disconnection between where and when neutron data is obtained and where and when x-ray data is obtained. If the relevant beamlines at ESS and MAX lab can figure out a way to offer integrated support to MX users, that would be a significant step forward in the field.

 

Monday 27 September 2021, 13:45 CET
Combined use of photons, neutrons, and electrons to unravel molecular details of the myelin membrane

Speaker: Prof Petri Kursula, Department of Biomedicine, University of Bergen, Norway
Host: Dr Tomás Plivelic, manager at CoSAXS beamline

Keywords: self-assembling repetitive molecular assemblies, myelin, biophysics, structural biology

Biological structures with self-assembling repetitive molecular assemblies are intriguing subjects for structural biology research. But how do such biostructures form and function at the molecular level? My model system is myelin, a tightly packed multilayer important for the normal functioning of the vertebrate nervous system. Myelin consists of dozens of proteolipid membrane layers, wrapped by a glial cell around the axon, and myelin-specific proteins are directly involved in binding of myelin membranes together. Our research focuses on the structure and properties of myelin-like membrane multilayers at different levels of detail. We use a combination of techniques, ranging from biophysics to structural biology, and experiments at large-scale research infrastructures are crucial for the project. I will describe the molecular structure of the myelin membrane and discuss our recent results and future plans with regard to more detailed studies on the molecular properties of myelin. Such information will be crucial for understanding both the molecular biology of myelin formation as well as mechanisms of demyelinating disease.

 

Monday 21 June 2021, 13:45 CET
Current and future X-ray imaging capabilities of MAX IV

Speaker: Dr Pablo Villanueva Pérez, Associate Senior Lecturer, Synchrotron Radiation Research, Lund University, Sweden
Host: Dr Maik Kahnt, scientist at NanoMAX beamline

Keywords: Coherent X-ray imaging, high-brilliance sources, 3D and 4Dimaging

MAX IV is the first diffraction-limited storage ring in operation. The high coherent flux or brilliance provided by diffraction-limited storage rings opens the opportunity to explore nature in ways not possible before. A technique that exploits the unique brilliance of MAX IV is coherent X-ray imaging.

In this talk, we will discuss the current coherent X-ray imaging capabilities of MAX IV by exploiting the nanofocus provided by NanoMAX. Specifically, we will present in-line holography and holotomography and its potential use as a stand-alone or correlative-microscopy technique. Furthermore, we will present future imaging capabilities of MAX IV by introducing X-ray multi-projection imaging (XMPI). XMPI is a novel imaging that can film in 3D natural processes 100 times faster than current 3D X-ray imaging techniques by exploiting single MAX IV X-ray pulses. XMPI will be developed in collaboration with DanMAX, ForMAX, and the European XFEL.

 

Monday 14 June 2021, 13:45 CET
A scattering model for the photosynthetic membranes of symbiotic algae in corals during simulated coral bleaching

Speaker: Dr Robert Corkery, Applied Physical Chemistry, KTH Royal Institute of Technology, Sweden
Host: Dr Ana María Labrador García, UO science officer

Keywords: small-angle scattering (SAXS/SANS), reef-building corals bleaching, geology

We present a model for scattering from the thylakoid structures of Symbiodinium cells. We compare the model to experimental scattering data (SANS) obtained from living Symbiodinium cells extracted from a branching reef-building coral, Acropora and extracted from, and living within the anemone, Aiptasia. Further experimental data was collected while simulating thermal bleaching. We interpret the changes in scattering as particular changes in thylakoid structure with help of the model and comment on the significance of our work in coral bleaching research.

 

Monday 7 June 2021, 13:45 CET
From molecules to nanoparticles, from gas-phase to liquids – X-ray spectroscopies across states of matter

Speaker: Assoc Prof Minna Patanen, Nano and Molecular Systems Research Unit, University of Oulu, Finland
Host: Dr Noelle Walsh, scientist at FlexPES beamline

Keywords: gas-phase nanoparticles, X-ray spectroscopy, multiplatform research

X-ray spectroscopies are excellent tools to study electronic structure of matter in all its states. Nowadays, a deep understanding of certain material or process necessitates knowledge of the spectroscopic properties of not only the system itself, but e.g. its building blocks or the surrounding environment, and often in a wide range of X-ray energies. From a perspective of a synchrotron user, this kind of multiplatform research would benefit from facile access to different beamlines and movable sample delivery systems. I will give recent examples of our gas-phase nanoparticle studies necessitating use of different sample environments, beamlines, and facilities (FinEstBeAMS, FlexPES, and other synchrotrons and lab sources).

 

Monday 24 May 2021, 13:45 CET
X-ray absorption spectroscopy on hydrated metal ions – Structure information beyond crystallography

Speaker: Prof Ingmar Persson, Department of Molecular Sciences, Swedish University of Agricultural Science (SLU), Sweden
Host: Dr Kajsa Sigfridsson Clauss, scientist at Balder beamline

Keywords: metal complexes, crystalline materials, X-ray absorption spectroscopy

X-ray absorption spectroscopy is an invaluable tool to study the structure around atoms in non-crystalline phases as solutions and amorphous materials. In this presentation I will show that this also may be the case for crystalline materials crystallizing in high symmetry space groups. Metal complexes with low symmetry may due to disorder crystallize in space groups with higher symmetry than the individual complexes. As EXAFS is a lattice independent structure method, metal-ligand bond distances can be determined with high accuracy independent of the structural order of the solid. This will be exemplified with studies on hydrated copper(II) and lanthanide(III) ions in aqueous solution and solid state [1,2].

[1] I. Persson, D. Lundberg, É. G. Bajnoczi, K. Klementiev, J. Just and K. G. V. Sigfridsson Clauss, EXAFS study on the coordination chemistry of the solvated copper(II) ion in a series of oxygen donor solvents. Inorg. Chem. 2020, 59, 9538-9550; doi: 10.1021/acs.inorgchem.0c00403.
[2] I. Persson, P. D’Angelo, S. De Panfilis, M. Sandström and L. Eriksson, Hydration of the Lanthanoid(III) Ions in Aqueous Solution and Crystalline Hydrates Studied by EXAFS Spectroscopy and Crystallography. The Myth of the “Gadolinium Break”. Chem. Eur. J. 2008, 14, 3056-3066; doi: 10.1002/chem.200701281

 

Monday 17 May 2021, 13:45 CET
Catalytic Conversion of Acetic Acid to Ketene on Cu2O(100)

Speaker: Prof Jonas Weissenrieder, Materials and Nano Physics, Applied Physics, KTH, Sweden
Host: Dr Andrey Shavorskiy, manager at HIPPIE beamline

Keywords: heterogeneous catalysis, x-ray photoelectron spectroscopy, green catalysis

The chemical flexibility of Cu2O, that allows for facile storage or release of oxygen atoms, has rendered reactions over its surface a topic of great interest for heterogeneous catalysis. I will present results from studies of chemical reactions taking place over Cu2O(100), starting with a description of the atomic structure of the surface. Special attention will be devoted to the synthesis of ketene from acetic acid over the (3,0;1,1) surface of Cu2O(100). Analysis of the adsorption and desorption characteristics of formic and acetic acids allow us to establish the reaction mechanism for ketene formation. Observations from x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy, and temperature programmed desorption (TPD), supported by a comparison with formic acid results, suggest that acetic acid reacts with Cu2O through deprotonation to form acetate species coordinated to copper sites and hydroxylation of nearby surface oxygen sites. For formic acid the decomposition of adsorbed formate species results in desorption of CO2 and CO while, for acetic acid, high yields of ketene are observed at temperature > 500 K. Modeling by density functional theory (DFT) confirms the strong interaction of acetic acid with the (3,0;1,1) surface and the spontaneous dissociation into adsorbed acetate and hydrogen atom species, the latter forming an OH-group. In an identified reaction intermediate (XPS and DFT) ketene binds via all C and O atoms to Cu surface sites. In the vicinity of the adsorbate the surface experiences a local reorganization into a c(2×2) reconstruction. The total computed energy barrier for ketene formation is 1.81 eV in good agreement with the 1.74 eV obtained from TPD analysis. Our experimental observations and mechanistic DFT studies suggests that Cu2O can operate as an efficient catalyst for the green generation of ketene from acetic acid.

 

Monday 10 May 2021, 13:45 CET
Time-resolved luminescence spectroscopy in studies of ultrafast processes in scintillators

Speaker: Prof Marco Kirm, Department of Natural and Exact Sciences, Institute of Physics, University of Tartu, Estonia
Host: Dr Antti Kivimäki, manager at FinEstBeAMS beamline

Keywords: Ultrafast scintillators, Time-resolved luminescence spectroscopy, novel hexafluorogermanate scintillators

Ultrafast scintillators with a superior temporal resolution are needed in different applications: in high-energy physics to prevent pile-up effects at high event rates as well as in time-of-flight positron emission tomography to improve the resolution in diagnostic images in medicine. In order to develop such materials extensive knowledge is needed on their electronic band structure verified with experimental spectroscopic data in a wide energy range. Time-resolved luminescence spectroscopy is an indispensable tool in studies of wide gap scintillators, in particular, the peculiarities of relaxation processes of electronic excitations and their time evolution. In order to study ultrafast processes, experimental facilities with sub-nanosecond time resolution are needed. Such setups have been successfully implemented at FinEstBeAMS and FemtoMAX, where the instrumental response function as short as 160 ps (in single bunch mode) and 28 ps, respectively, were achieved. Based on the results obtained at these setups by time-resolved luminescence methods, I will discuss the relaxation processes of electronic excitations in novel hexafluorogermanate scintillators leading to the ultrafast cross- and intraband luminescence with sub-nanosecond lifetime.

 

Monday 3 May 2021, 13:45 CET
Solution structure and self-association of pharmaceutical proteins

Speaker: Prof Pernille Harris, Department of Chemistry, University of Copenhagen, Denmark
Host: Dr Ann Terry, Diffraction and Scattering Group Manager, CoSAXS beamline

Keywords: small-angle X-ray scattering, protein-protein interactions, protein formulation, protein aggregation

The use of small angle X-ray scattering as a powerful method for investigating protein structure and complex formation in ideal solutions has been established and refined the last decades. SAXS is used more or less routinely as a supplement to other structural investigations or even as a standalone technique for structural information. However, SAXS is much more than that. It is also a biophysical technique that can be used for high-throughput characterization and for investigations of protein-protein interactions in high-concentration samples.

We are successfully using SAXS in different ways to characterize proteins in pharmaceutically relevant solutions, combining it with other high-throughput techniques and in-silico modeling.

 

Monday 26 April 2021, 13:45 CET
Scanning transmission X-ray microscopy for organic photovoltaics

Speaker: Dr Erik Mårsell, Postdoc at SoftiMAX beamline, MAX IV, Lund University, Sweden
Host: Dr Karina Thånell, manager at SoftiMAX beamline

Keywords: organic photovoltaics, solar cells , scanning transmission X-ray microscopy

Organic photovoltaics shows great promise for lightweight, low-cost, flexible solar cells with low embodied energy. However, the power conversion efficiency is currently too low for widespread commercial success. Furthermore, questions remain regarding the long-term stability of devices under typical operation conditions. To address these questions, we need to further investigate the electronic and morphologic structure of the donor-acceptor molecular blends responsible for light absorption and electron-hole separation. I will describe SoftiMAX and its scanning transmission X-ray microscopy (STXM) end station, and how it can be used to study organic photovoltaic devices. STXM has the capability to simultaneously measure the morphology, composition, and crystallinity of the active layer, potentially under operational conditions. These parameters can then be correlated with growth conditions and device efficiencies to better understand how to improve organic solar cells.

 

Monday 19 April 2021, 13:45 CET
Water uptake at low relative humidity onto atmospherically relevant nanoparticles studied with APXPS

Speaker: Dr Jack Lin, Nano and Molecular Systems Research Unit, University of Oulu, Finland
Host: Dr Esko Kokkonen, manager at SPECIES beamline

Keywords: serial ambient pressure X-ray photoelectron spectroscopy (APXPS); atmospheric aerosols; atmospheric chemistry; water

The interaction between particulate matter and water is important to several atmospheric processes, including atmospheric chemistry and cloud formation, that have an impact on climate, air quality, and the water cycle. Traditional atmospheric measurement techniques that rely on detecting changes in mass or volume are not sensitive to the adsorption of water at low relative humidity (RH). We used APXPS to study laboratory generated nanoparticles of atmospheric interest at 0-16% RH. Our results suggest the possibility of water adsorption to the particle surface even at RH well below deliquescence which has implications for atmospheric chemistry.

 

Monday 12 April 2021, 13:45 CET
Operando observation of reversible oxygen migration and phase transitions in ferroelectric Hf0.5Zr0.5O2 thin films

Speaker: Dr Pavan Nukala, Center for Nanoscience and Engineering, Indian Institute of Science, India
Host: Dr Alexander Björling, scientist at NanoMAX beamline

Keywords: nanoelectronics, atomic resolution electron microscopy, in situ electrical biasing, nanobeam x-ray diffraction

Unconventional ferroelectricity, robust at reduced nanoscale sizes, exhibited by hafnia-based thin-films presents tremendous opportunities in nanoelectronics. However, the exact nature of polarization switching remains controversial. We investigated epitaxial Hf0.5Zr0.5O2 (HZO) capacitors, interfaced with oxygen conducting metals (La0.67Sr0.33MnO3, LSMO) as electrodes, using atomic resolution electron microscopy while in situ electrical biasing and operando nanobeam x-ray diffraction at NanoMAX beamline. In the past, our group has discovered a new structural phase in epitaxial samples of HZO grown using pulsed laser depostion which show increasing polarization with decreasing sizes, all the way upto record values of 35 uc/cm2 (for 6 nm thick film) [1]. We utilize differential phase contrast STEM imaging in conjunction with in situ biasing, and follow directly interpretable oxygen dynamics at an atomic scale, albeit under DC stressing conditions. Through operando XRD measurements, we follow the evolution of the Bragg peaks of HZO (and LSMO) on the 2D detector with 1 ms resolution upon cycling the devices at 100 Hz. These measurements unravel oxygen migration assisted short-term ferroelectric switching dynamics and electromechanical properties of HZO.

[1] P. Nukala et al., Operando observation of reversible oxygen migration and phase transitions, arXiV.2010.10849 (2020)

 

Extraordinary SCIENTÍFika session

Tuesday 30 March 2021, 16:00 CET 

How do intruders take over their hosts?

Speaker: Prof Ada Yonath, Nobel Prize in Chemistry in 2009
Host: Dr. Christine Darve, engineering scientist at European Spallation Source (ESS)

Synchrotron radiation and Cryo EM illuminated the basic life process: the translation of the genetic code. In a still unclear mechanism, the viruses, which lack such systems, take over their hosts machinery for replicating themselves.

Thanks to all who participated to the extraordinary SCIENTÍFika session hosting Nobel Prize laureate in Chemistry in 2009 Prof Ada Yonath on March 30th, we were glad to see such a numerous audience! It was a great honor and pleasure to have the opportunity to hear Prof Yonath´s inspiring experience and chat about open scientific questions!

 

 

Monday 29 March 2021, 13:45 CET
Mass extinctions in Earth´s history through Balder and NanoMax

Speaker: Prof Vivi Vajda, Paleontology Department, Swedish Museum of Natural History, Sweden

Host: Dr Kajsa Sigfridsson Clauss, scientist at Balder beamline

Keywords: fossils, asteroids, vibrational microspectroscopy methods

The composition of fossil leaves  and organelles in fossilised plants from the Jurassic was recently revealed through multiple vibrational microspectroscopy methods (FT-IR, Raman) at MAX IV, showing that these methods can provide information on fossilised organic matter.

Our next project aims to geochemically analyse asteroid impact spherules and sediments formed when the Chicxulub crater was excavated by an asteroid, 66 million years ago causing the extinction of, amongst others, the dinosaurs. The chemical mapping of the spherules contributes with knowledge on the distribution of elements in the silica spherules, providing information on the composition of the Asteroid. We further use XANES spectra of the different relevant elements to detect event beds of different age where extinctions have occurred, aiming at providing clues concerning the triggering mechanisms behind these events – volcanism or asteroids??

 

Monday 22 March 2021, 13:45 CET

Magnetic Materials and Topology

Speaker: Prof Claudia Felser, Max Planck Institute for Chemical Physics of Solids, Germany
Host: Dr. Craig Polley, scientist at BLOCH beamline

Keywords: topology, magnetic materials, angle-resolved photoemission

Topology, a mathematical concept, recently became a hot and truly transdisciplinary topic in condensed matter physics, solid state chemistry and materials science. All 200 000 inorganic materials were recently classified into trivial and topological materials: topological insulators, Dirac, Weyl and nodal-line semimetals, and topological metals [1]. Around 20% of all materials host topological bands. Currently, we have focused also on magnetic materials, a fertile field for new since all crossings in the band structure of ferromagnets are Weyl nodes or nodal lines [2], as for example Co2MnGa and Co3Sn2S2. Beyond a single particle picture and identified antiferromagnetic topological materials [3].

[1] Bradlyn et al., Nature 547  298, (2017), Vergniory, et al., Nature 566 480 (2019).
[2] Belopolski, et al., Science 365, 1278 (2019), Liu, et al. Nature Physics 14, 1125 (2018), Guin, et al. Advanced Materials 31 (2019) 1806622, Liu, et al., Science 365, 1282 (2019), Morali, et al., Science 365, 1286 (2019)
[3] Xu et al. Nature 586 (2020) 702.

 

Monday 15 March 2021, 13:45 CET
Multimodal and Coherent X-ray imaging techniques for thin-film solar cell research

Speaker: Prof Jens Wenzel Andreasen, Department of Energy Conversion and Storage, Technical University of Denmark, Denmark
Host: Dr. Innokenty Kantor, manager at DanMAX beamline

Keywords: thin-film solar cells, X-ray imaging
3rd generation solar cells are often polycrystalline and with a complex chemistry. Common to all thin-film solar cell technologies is the strong correlation between device performance and nano-structure of the photo-active layer, interfaces and electrodes. With a combination of several modalities, X-ray imaging techniques can probe the most important physical properties of such devices, even during operation. We have demonstrated this on samples and working devices of Copper Zinc Tin Sulfide (CZTS) solar cells. The applied techniques include combinations of resonant X-ray ptychographic tomography [1], X-ray Beam Induced Current, scanning X-ray fluorescence and 3D X-ray Diffraction.
[1] Fevola et al. (2020) Phys. Rev. Res. 2, 013378. https://doi.org/10.1103/PhysRevResearch.2.013378

 

Monday 8 March 2021, 13:45 CET
Towards a more affordable solar cell: Molecular scale techniques as a tool to improve long term stability and efficiency on solar absorbing layer nanocrystals

Speaker: Associate Professor Arnaldo Naves de Brito, Applied Physics Department, University of Campinas, Brazil
Host: Dr. Gunnar Öhrwall, scientist at FlexPES beamline

Keywords: lumiscent nanocrystals, solar cells, electron spectroscopy

Highly luminescent Cesium Lead Halide Perovskites Nano-Crystals (CLHP-NCs), CsPbX3 X=Cl,Br,I, are a promising new-comer as solution-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. CLHP-NCs are cheap to produce but still suffer from low colloidal and phase stability. Besides, molecular engineering of its bandgap is crucial for its su
ccess in the clean energy field. In July 2020, we inaugurated electron spectroscopy (ES) on NCs diluted in non-polar liquids.  In this talk, we show how ES can provide valuable information, on a molecular scale, to guide new synthesis strategies for more stable and efficient CLHP-NCs.

 

Monday 1 March 2021, 13:45 CET
Developing materials for the quantum anomalous Hall effect: From extrinsic to intrinsic magnetic topological insulators

Speaker: Prof Oliver Rader, Department Spin and Topology in Quantum Materials, Helmholtz-Zentrum Berlin (BESSY II), Germany
Host: Dr. Evangelos Golias, scientist at MAXPEEM beamline

Keywords: ferromagnetic topological insulators, angle-resolved photoemission
Ferromagnetic topological insulators have been used to demonstrate the quantum anomalous Hall (QAH) effect which may find applications in lossless device interconnects, spintronics, and topological qubits. The materials were Cr and V doped topological insulators, however the QAH effect appeared only for temperatures up to 1 K, much lower than the principle limit given by the Curie temperature of the materials. Another key parameter is the size of the magnetic gap at the Dirac point of the topological surface state which, however, has never been observed directly by spectroscopic means. We use angle-resolved photoemission with and without spin resolution to reveal the magnetic gap in the topological insulators MnBi2Te4/Bi3Te4 and MnSb2Te4. We point out the role of the valency of the magnetic dopant for the structure, what the structure in turn means for the size of the magnetic gap, and shed light on the role of the spin orbit interaction for the gap formation. It is shown that MnSb2Te4 is a topological insulator where the magnetic gap can be followed up to the record-high Curie temperature of 50 K and where disorder plays a surprising role.

 

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 Kivimäki, 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.

 

Monday 15 February 2021, 13:45 CET
High-Resolution Resonant Inelastic Soft X-Ray Scattering on Small Molecules: An Overview of Recent Results and Opportunities at MAX IV

Speaker: Prof Jan-Erik Rubensson, Department of Physics and Astronomy, Molecular and Condensed Matter Physics, Uppsala University, Sweden
Host: Dr Victor Ekholm, scientist at VERITAS beamline

Keywords: resonant inelastic soft X-ray scattering (RIXS), small molecules, ultrafast electronic-vibronic dynamics
Visions for resonant inelastic soft X-ray scattering (RIXS) applied to small molecules will be discussed, and some recent results presented. The importance of dipole selection rules in the investigation of ultrafast electronic-vibronic dynamics will be emphasized. Emerging opportunities at VERITAS, due to the very high energy resolution, the polarization control in both incident and scattered radiation, and the availability of a large range of scattering angles will be discussed.

 

Monday 8 February 2021, 13:45 CET
Serial crystallography as a tool to study protein structure and dynamics

Speaker: Associate Professor Gisela Brändén, Department of Chemistry & Molecular Biology, University of Gothenburg, Sweden
Host: Monika Bjelcic, PhD student at 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 1 February 2021, 13:45 CET
Permanent magnets a challenge of size, shape, and orientation  

Speaker: Associate Professor 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 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 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 have 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 fibers 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 fibers 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, 14 December 2020 at 13:45 CET
Electronically driven spin-reorientation transition of the correlated polar metal Ca3Ru2O7

Speaker: Prof Philip King, School of Physics and Astronomy, University of St. Andrews, UK
Host: Dr. Craig Polley, scientist at the BLOCH beamline

Keywords: spin-orbit coupling in solids, angle-resolved photoemission spectroscopy
The influence of spin-orbit coupling in solids has become the subject of much attention in recent years. When combined with a breaking of inversion symmetry, it can lift the spin degeneracy of electronic states via the so-called Rashba effect, with potential applications in spin-generation and manipulation, spin-transfer torques, and the formation of topological states.1 Here, using angle-resolved photoemission spectroscopy, I will demonstrate how Rashba-type spin-orbit interactions mediate a dramatic reconstruction of the Fermi surface accompanying at a spin-reorientation phase transition in the correlated polar metal Ca3Ru2O7,2 pointing to a new form of magneto-electronic coupling, and highlighting the delicate balance between symmetry-breaking, electronic correlations, and spin-orbit coupling in solids.
Manchon et al., Nature Materials 14 (2015) 871
Marković et al., PNAS 117 (2020) 15524