Scientific Highlights 2018

11 July 2018

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On the path to new high-performance transistors

Media Releases Research Using Synchrotron Light Large Research Facilities Materials Research

The electronics industry expects a novel high-performance transistor made of gallium nitride to offer considerable advantages over present-day high-frequency transistors. Yet many fundamental properties of the material remain unknown. Now, for the first time, researchers at the Paul Scherrer Institute PSI have observed electrons while they were flowing in this promising transistor. For that they used one of the world's best sources of soft X-rays at PSI's Swiss Light Source SLS.

20 June 2018

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Movie directors with extra roles

SwissFEL Storage Large Research Facilities

Data storage devices based on novel materials are expected to make it possible to record information in a smaller space, at higher speed, and with greater energy efficiency than ever before. Movies shot with the X-ray laser show what happens inside potential new storage media, as well as how the processes by which the material switches between two states can be optimised.

20 June 2018

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MOOCs – a paradigm shift in education

In March 2018, the nine-week MOOC “Introduction to synchrotrons and x-ray free-electron lasers” (abbreviated to “SYNCHROTRONx”) came online via the edX provider of the École Polytechnique Fédérale de Lausanne (EPFL), created by Phil Willmott of the Swiss Light Source, Paul Scherrer Institute. “MOOC” is an acronym for “massive open online course”, a teaching platform started in the first decade of this century, which has become increasingly popular in the last five to six years. MOOCs have no limits to participation and are free. Some of the most popular MOOCs can attract many tens of thousands of participants. Even the most specialized subjects may have an initial enrollment of over a thousand, more than an order of magnitude larger than that typically found in traditional higher education. There were over 70 million MOOC enrollments covering nearly 10’000 subjects offered by the top five providers in 2017 alone!

16 May 2018

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Creation and deletion of isolated magnetic skyrmions via electrical currents

The writing and deletion of magnetic Skyrmions is a fundamental step towards the fabrication of memory devices based on this promising spin configuration. Researchers at the Korea Institute of Technology have demonstrated the writing and deleting of isolated magnetic Skyrmions at room temperature in ferrimagnetic multilayer superlattice stacks using electrical currents.

7 May 2018

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Fresnel Zone Plates with Zone Widths below 10 nm

The spot size of a Fresnel Zone Plate lens is mainly determined by the zone widths of its outermost zone. It is therefore essential to fabricate zone plates with structures as small as possible for high-resolution X-ray microscopy. Researchers at the Laboratory for Micro- and Nanotechnology at the PSI have now developed Fresnel zone plates with zone widths well below 10 nm, down to 6.4 nm. These lenses are capable of pushing resolution in X-ray microscopy to the single-digit regime.

19 March 2018

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HERCULES at the Swiss Light Source

In the week of March 18-23 PSI welcomes 20 PhD students and postdocs taking part in the HERCULES 2018 school on Neutron and Synchrotron Radiation. They will attend lectures and perform two days of practical courses at several beam lines of the Swiss Light Source.

27 February 2018

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Are supersaturated calcium carbonate solutions classical or non-classical ?

Classical theory predicts that supersaturated carbonate solutions consist mostly of ions and ion pairs, with a small number of larger clusters present in the solution. The population of the different sized clusters in a solution is solely defined by the cluster’s size dependent Free Energy. If clusters are large enough they serve as nucleation germs for a new solid phase. The nucleation occurs once the surface free energy barrier posed by the new solid-liquid interface is overcome by the free energy win from bulk phase growth. However, for calcium carbonate solutions, this classical view has been challenged by the emergence of non-classical theories. In a novel experiment, using synchroton X-ray absorption spectroscopy, the molecular structure around the solvated calcium ion in dilute supersaturated calcium carbonate solutions was probed in situ. The results obtained definitively show that supersaturated calcium carbonate solutions are dominated by ions and ion pairs. The presence of larger oligomers as predicted by non-classical theories was not detected. Moreover, predictions from independent theoretical calculations on the structure of supersaturated calcium carbonate solutions were in congruence with the experimental results. As a consequence, it is quite clear that the nucleation of calcium carbonate follows a classical pathway.

29 January 2018

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Unravelling structure sensitivity in CO2 hydrogenation over nickel

Using a unique set of well-defined silica-supported Ni nanoclusters (1–7 nm) and advanced characterization methods it was proved how structure sensitivity influences the mechanism of catalytic CO2 reduction, the nature of which has been long debated.