International Evaluation of the Finnish Geospatial Research Institute, FGI

This is the report of an international panel for the 2022 Evaluation of the Finnish Geospatial Research Institute (FGI). The Ministry of Agriculture and Forestry commissioned a team of proven scientists and science managers to review the FGI's activities and competencies and make recommendations for the coming years. The evaluation panel focused their work on 1) the quality of research and expert work of FGI, 2) FGI's societal impacts and relevance to society (public sector, private companies, citizens), 3) FGI's activity and leadership in research collaboration and networks and 4) foresight and innovativeness of FGI's activities. The evaluation panel prepared a description of FGI's strengths, weaknesses, threats and opportunities. In addition, the panel made suggestions and recommendations for further development of FGI's research and expert work

Bench-top X-ray microtomography complemented with spatially localized X-ray scattering experiments

This article describes a novel experimental setup that combines X-ray microtomography (XMT) scans with in situ X-ray scattering experiments in a laboratory setting. Combining these two methods allows the characterization of both the micrometre-scale morphology and the crystallographic properties of the sample without removing it from the setup. Precise control of the position of the sample allows an accurate choice of the scattering beam path through the sample and facilitates the performance of X-ray scattering experiments on submillimetre-sized samples. With the present setup, a voxel size of less than 0.5 mm is achievable in the XMT images, and scattering experiments can be carried out with a beam size of approximately 200 200 mm. The potential of this setup is illustrated with the analysis of micrometeorite crystal structure and diffraction tomographic imaging of a silver behenate phantom as example applications.Peer reviewe

The isotropic Compton profile difference across the phase transition of VO2_2

We studied the isotropic Compton profile of the prototypical oxide VO$_2$ across the temperature induced electronic and structural phase transition at T$_C$ $\approx$ 340 K. We show that the phase transition leaves an observable signal, which facilitates Compton scattering studies of electronic structure and phase transitions in complex solids in powder form. We compare the experimental results with density functional theory calculations and find agreement in the shape of the difference profile, although the amplitude of the observed features is overestimated. The origin of the disagreement is discussed and we argue that it mainly originates mostly correlation effects beyond our current calculations and possibly to some extent, from thermal motion

Tetrahydrofuran Clathrate Hydrate Formation

We report on the formation of tetrahydrofuran clathrate hydrate studied by x-ray Raman scattering measurements at the oxygen K edge. A comparison of x-ray Raman spectra measured from water-tetrahydrofuran mixtures and tetrahydrofuran hydrate at different temperatures supports stochastic hydrate formation models rather than models assuming hydrate precursors. This is confirmed by molecular dynamics simulations and density functional theory calculations of x-ray Raman spectra. In addition, changes in the spectra of tetrahydrofuran hydrate with temperatures close to the hydrate's dissociation temperature were observed and may be connected to changes in hydrate's local structure due to the formation of hydrogen bonds between guest and water molecules.We report on the formation of tetrahydrofuran clathrate hydrate studied by x-ray Raman scattering measurements at the oxygen K edge. A comparison of x-ray Raman spectra measured from water-tetrahydrofuran mixtures and tetrahydrofuran hydrate at different temperatures supports stochastic hydrate formation models rather than models assuming hydrate precursors. This is confirmed by molecular dynamics simulations and density functional theory calculations of x-ray Raman spectra. In addition, changes in the spectra of tetrahydrofuran hydrate with temperatures close to the hydrate's dissociation temperature were observed and may be connected to changes in hydrate's local structure due to the formation of hydrogen bonds between guest and water molecules.We report on the formation of tetrahydrofuran clathrate hydrate studied by x-ray Raman scattering measurements at the oxygen K edge. A comparison of x-ray Raman spectra measured from water-tetrahydrofuran mixtures and tetrahydrofuran hydrate at different temperatures supports stochastic hydrate formation models rather than models assuming hydrate precursors. This is confirmed by molecular dynamics simulations and density functional theory calculations of x-ray Raman spectra. In addition, changes in the spectra of tetrahydrofuran hydrate with temperatures close to the hydrate's dissociation temperature were observed and may be connected to changes in hydrate's local structure due to the formation of hydrogen bonds between guest and water molecules.Peer reviewe

Resonant X-ray emission with a standing wave excitation

The Borrmann effect is the anomalous transmission of x-rays in perfect crystals under diffraction conditions. It arises from the interference of the incident and diffracted waves, which creates a standing wave with nodes at strongly absorbing atoms. Dipolar absorption of x-rays is thus diminished, which makes the crystal nearly transparent for certain x-ray wave vectors. Indeed, a relative enhancement of electric quadrupole absorption via the Borrmann effect has been demonstrated recently. Here we show that the Borrmann effect has a significantly larger impact on resonant x-ray emission than is observable in x-ray absorption. Emission from a dipole forbidden intermediate state may even dominate the corresponding x-ray spectra. Our work extends the domain of x-ray standing wave methods to resonant x-ray emission spectroscopy and provides means for novel spectroscopic experiments in d- and f-electron systems.Peer reviewe

Inelastic x-ray scattering in heterostructures : electronic excitations in LaAlO3/SrTiO3

Peer reviewe