Author
Marco Calvi
Bio: Marco Calvi is an academic researcher from Paul Scherrer Institute. The author has contributed to research in topics: Undulator & Beamline. The author has an hindex of 13, co-authored 54 publications receiving 993 citations.
Topics: Undulator, Beamline, Free-electron laser, Magnetic field, Magnet
Papers published on a yearly basis
Papers
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TL;DR: The SwissFEL X-ray Free Electron Laser (XFEL) facility as discussed by the authors started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users in 2018 on the Aramis hard Xray branch.
Abstract: The SwissFEL X-ray Free Electron Laser (XFEL) facility started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users in 2018 on the Aramis hard X-ray branch. In the following sections we will summarize the various aspects of the project, including the design of the soft and hard X-ray branches of the accelerator, the results of SwissFEL performance simulations, details of the photon beamlines and experimental stations, and our first commissioning results.
295 citations
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TL;DR: The wiggler X-ray source of the Materials Science beamline at the Swiss Light Source has been replaced with a 14 mm-period cryogenically cooled in-vacuum undulator to best exploit the increased brilliance of this new source.
Abstract: The Materials Science beamline at the Swiss Light Source has been operational since 2001 In late 2010, the original wiggler source was replaced with a novel insertion device, which allows unprecedented access to high photon energies from an undulator installed in a medium-energy storage ring In order to best exploit the increased brilliance of this new source, the entire front-end and optics had to be redesigned In this work, the upgrade of the beamline is described in detail The tone is didactic, from which it is hoped the reader can adapt the concepts and ideas to his or her needs
259 citations
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TL;DR: The beamline commissioning measurements, which show a resolving power of 8000 and a maximum flux at the sample of 4.7 × 10(12) photons s(-1), are presented and scientific examples showing X-ray magnetic circular and X-Ray magnetic linear dichroism measurements are presented.
Abstract: X-Treme is a soft X-ray beamline recently built in the Swiss Light Source at the Paul Scherrer Institut in collaboration with Ecole Polytechnique Federale de Lausanne. The beamline is dedicated to polarization-dependent X-ray absorption spectroscopy at high magnetic fields and low temperature. The source is an elliptically polarizing undulator. The end-station has a superconducting 7 T–2 T vector magnet, with sample temperature down to 2 K and is equipped with an in situ sample preparation system for surface science. The beamline commissioning measurements, which show a resolving power of 8000 and a maximum flux at the sample of 4.7 × 1012 photons s−1, are presented. Scientific examples showing X-ray magnetic circular and X-ray magnetic linear dichroism measurements are also presented.
145 citations
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TL;DR: In this article, the first lasing results of SwissFEL, a hard X-ray free-electron laser (FEL) that recently came into operation at the Paul Scherrer Institute in Switzerland, were presented.
Abstract: We present the first lasing results of SwissFEL, a hard X-ray free-electron laser (FEL) that recently came into operation at the Paul Scherrer Institute in Switzerland. SwissFEL is a very stable, compact and cost-effective X-ray FEL facility driven by a low-energy and ultra-low-emittance electron beam travelling through short-period undulators. It delivers stable hard X-ray FEL radiation at 1-A wavelength with pulse energies of more than 500 μJ, pulse durations of ~30 fs (root mean square) and spectral bandwidth below the per-mil level. Using special configurations, we have produced pulses shorter than 1 fs and, in a different set-up, broadband radiation with an unprecedented bandwidth of ~2%. The extremely small emittance demonstrated at SwissFEL paves the way for even more compact and affordable hard X-ray FELs, potentially boosting the number of facilities worldwide and thereby expanding the population of the scientific community that has access to X-ray FEL radiation. The first lasing results at SwissFEL, an X-ray free-electron laser, are presented, highlighting the facility’s unique capabilities. A general comparison to other major facilities is also provided.
118 citations
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TL;DR: An overview is given of the SwissFEL soft X-ray free-electron laser (FEL) beamline, called Athos, and its numerous operation modes, and several key hardware components, which enable these modes.
Abstract: The SwissFEL soft X-ray free-electron laser (FEL) beamline Athos will be ready for user operation in 2021. Its design includes a novel layout of alternating magnetic chicanes and short undulator segments. Together with the APPLE X architecture of undulators, the Athos branch can be operated in different modes producing FEL beams with unique characteristics ranging from attosecond pulse length to high-power modes. Further space has been reserved for upgrades including modulators and an external seeding laser for better timing control. All of these schemes rely on state-of-the-art technologies described in this overview. The optical transport line distributing the FEL beam to the experimental stations was designed with the whole range of beam parameters in mind. Currently two experimental stations, one for condensed matter and quantum materials research and a second one for atomic, molecular and optical physics, chemical sciences and ultrafast single-particle imaging, are being laid out such that they can profit from the unique soft X-ray pulses produced in the Athos branch in an optimal way.
53 citations
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TL;DR: This work reports a facile colloidal synthesis method for obtaining FAPbI3 and FA-doped CsPbI 3 NCs that are uniform in size and nearly cubic in shape and exhibit drastically higher robustness than their MA- or Cs-only cousins with similar sizes and morphologies.
Abstract: Colloidal nanocrystals (NCs) of APbX3-type lead halide perovskites [A = Cs+, CH3NH3+ (methylammonium or MA+) or CH(NH2)2+ (formamidinium or FA+); X = Cl–, Br–, I–] have recently emerged as highly versatile photonic sources for applications ranging from simple photoluminescence down-conversion (e.g., for display backlighting) to light-emitting diodes. From the perspective of spectral coverage, a formidable challenge facing the use of these materials is how to obtain stable emissions in the red and infrared spectral regions covered by the iodide-based compositions. So far, red-emissive CsPbI3 NCs have been shown to suffer from a delayed phase transformation into a nonluminescent, wide-band-gap 1D polymorph, and MAPbI3 exhibits very limited chemical durability. In this work, we report a facile colloidal synthesis method for obtaining FAPbI3 and FA-doped CsPbI3 NCs that are uniform in size (10–15 nm) and nearly cubic in shape and exhibit drastically higher robustness than their MA- or Cs-only cousins with sim...
368 citations
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TL;DR: The SwissFEL X-ray Free Electron Laser (XFEL) facility as discussed by the authors started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users in 2018 on the Aramis hard Xray branch.
Abstract: The SwissFEL X-ray Free Electron Laser (XFEL) facility started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users in 2018 on the Aramis hard X-ray branch. In the following sections we will summarize the various aspects of the project, including the design of the soft and hard X-ray branches of the accelerator, the results of SwissFEL performance simulations, details of the photon beamlines and experimental stations, and our first commissioning results.
295 citations
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TL;DR: A study of the magnetic response of cobalt atoms adsorbed on oxide surfaces may lead to much denser storage of data, and the maximum magnetic anisotropy allowed for a transition metal atom is realized by coordinating a single Co atom to the O site of an MgO(100) surface.
Abstract: Designing systems with large magnetic anisotropy is critical to realize nanoscopic magnets. Thus far, the magnetic anisotropy energy per atom in single-molecule magnets and ferromagnetic films remains typically one to two orders of magnitude below the theoretical limit imposed by the atomic spin-orbit interaction. We realized the maximum magnetic anisotropy for a 3d transition metal atom by coordinating a single Co atom to the O site of an MgO(100) surface. Scanning tunneling spectroscopy reveals a record-high zero-field splitting of 58 millielectron volts as well as slow relaxation of the Co atom's magnetization. This striking behavior originates from the dominating axial ligand field at the O adsorption site, which leads to out-of-plane uniaxial anisotropy while preserving the gas-phase orbital moment of Co, as observed with x-ray magnetic circular dichroism.
295 citations
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TL;DR: An overview of different chemical complexes studied by X-ray magnetic circular dichroism (XMCD) is presented in this article, where the possibilities of this technique for the characterization of magnetically interesting systems are discussed.
265 citations