At an international conference in Berlin, researchers were discussing options for using X-rays to take time-resolved measurements
Scientists from all over the world discussed the challanges of messuring the dynamic processes in different materials with X-rays.
The participants.
The Helmholtz Virtual Institute “Dynamic pathways in multidimensional landscapes” is striving for a holistic view of material properties
In the heart of Berlin, 85 scientists came together on the occasion of an international conference in order to network as part of the Helmholtz Virtual Institute “Dynamic pathways in multidimensional landscapes” and gain new impulses for future research. The focus was on examining ultrafast dynamics within a broad material spectrum from molecules to nanostructures to strongly correlated solids. The conference took place from September 16 through 20 at the German Physical Society’s Magnus House in Berlin.
Using X-ray methods, the scientists are striving for a holistic view of different systems' properties determined by interactions among internal degrees of freedom and their interactions with the environment. The invited presentations covered the whole spectrum – from experimental aspects all the way to theoretical models. In that sense, the meeting of these different experts on the occasion of this conference was decidedly unique – and one of the virtual institute's key objectives. As such, every researcher from every available free electron laser (FEL) in the field of X-rays was represented. Over the last several years, FELs have established themselves as the single most important tool in the X-ray based study of ultrafast dynamics of matter. The SLAC’s Prof. Jo Stöhr gave a passionate talk on the major differences between interactions with matter of synchrotron light and FEL X-rays, respectively.
Stöhr is also scheduled to give a “Distinguished Lecture” on December 9, 2013, at the Helmholtz Zentrum Berlin.
The scientific scope of the conference included sessions on specific material classes and experimental techniques with a focus on:
- quantum materials, magnetism, and correlated solids
- molecular dynamics in physical chemistry and catalysis
- interactions of X-ray photons with matter
- atomic structural analysis using coherent scattering, diffraction and imaging
Attendees considered the poster session, where 26 submissions from junior researchers were being exhibited, a particular success. The posters helped reinforce the virtual institute’s breadth of research topics and prompted discussions.
As part of the Helmholtz Virtual Institute “Dynamic pathways in multidimensional landscapes,” scientists from the HZB, DESY, and from two German universities are together doing research on complex materials in collaboration with both national and international partners. Prof. Dr. Alexander Föhlisch is the spokeman of the virtual Helmholtz institute and leads the "Institute Methods and Instrumentation for Synchrotron Radiation Research" at HZB.
- BESSY II: New sample environment allows glimpse into thermocatalytic processesA novel measurement cell allows, for the first time, soft and hard X-ray investigations under high pressures of up to 20 bar and temperatures of up to 400°C. This provides new insights into thermocatalytic processes, such as the Fischer-Tropsch synthesis for producing synthetic fuels. The development of the measurement cell is considered a significant achievement within the Care-O-Sene project.
- Magnetic imaging: Micro-flowers increase the local magnetic fieldMaterials with magnetic nanostructures have many potential applications such as in spintronics. To explore such materials, nanoscale magnetic-sensitive imaging techniques are very useful, but up to now only weak magnetic fields could be applied during the imaging process. Now an international collaboration led by Dr. Sergio Valencia, HZB, has developed an approach that overcomes this limitation. The team designed tiny magnetic flux concentrators (MFCs), into which the sample is placed. The geometry of the MFCs resembles a flower with a number of petals which focus the applied magnetic field into its center. This greatly expands the magnetic field range available during imaging, and so the range of magnetic systems that can be investigated. The micro-flowers, enhancing magnetic fields locally, can find application in different nanometric magnetic microscopy techniques.
- Disorder creates new properties in compound semiconductorsAn international research team has demonstrated that the intrinsic disorder of the compound semiconductor CuInSnS₄ can be exploited to influence its optical properties. While the atomic vibrations also sense the local disorder, their response is averaged over many different local environments and therefore appear isotropic, as expected for a cubic crystal. In contrast, the optical excitations, known as excitons, are much more sensitive to the local arrangement of atoms. Surprisingly, they show a direction-dependent optical response even though the average crystal structure is cubic. These findings shed new light on the relationship between disorder and material properties, opening up new options for targeted 'disorder engineering' in optoelectronic and photocatalytic devices.