European XFEL starts operation of second X-ray light source

Another important milestone achieved in the development of the facility

The second X-ray light source has successfully been taken into operation at European XFEL, the world’s largest X-ray laser located in the Hamburg metropolitan region. The X-ray light source SASE3 successfully produced X-ray laser light flashes in one of the underground tunnels. SASE3 will serve two experiment stations scheduled to begin user operation at the end of the year. Since the start of operation in September 2017, 340 scientists from across the globe have already used the facility for their research. The successful start of operation of the new SASE 3 source will enable the facility to increase the number of users further.

European XFEL Managing Director Prof. Robert Feidenhans’ said: “The construction and commissioning of the new light source are complex processes, for which we and our DESY colleagues have been preparing intensely for these last weeks and months. We are very happy that the commissioning of this second light source SASE 3 has also run so smoothly, and that both sources, SASE1 and SASE3, produce light simultaneously. For this I would like to thank all those involved, in particular the accelerator team from DESY. We continue to be on schedule to start operation at all four experiment stations currently under construction, beginning with the first two instruments in November. The remaining two will start operation at the beginning of 2019. This will increase our current capacity threefold by mid 2019.”

>Read more on the European XFEL website

Image of the first X-ray laser beam in the tunnel from the European XFEL’s SASE3 undulator. SASE3 generates X-rays with a wavelength similar to the width of an atom. Those X-rays will be used to study subjects such as the formation and breaking of chemical bonds and the emergence of special properties such as semiconductivity in materials.

The microstructure of a parrotfish tooth contributes to its toughness

During a 2012 visit to the Great Barrier Reef off the coast of Australia, ALS staff scientist Matthew Marcus became intrigued with parrotfish. “I was reminded that this is a fish that crunches up coral all day and is responsible for much of the white sand on beaches,” Marcus said. “But how can this fish eat coral and not lose its teeth?” So Marcus teamed up with Pupa Gilbert, a biophysicist at the University of Wisconsin–Madison, and an international team of researchers she assembled, to understand how parrotfish teeth work.

Because conventional microscopes can overlook the unique orientation of crystals in tooth enamel, the team used the technique called polarization-dependent imaging contrast (PIC) mapping that Gilbert invented, which uses the photoemission electron microscopy (PEEM) Beamline 11.0.1 at the ALS. The PIC maps allowed them to visualize the orientation of individual crystals of fluorapatite, the main mineral component of parrotfish teeth.

Separate experiments used tomography (Beamline 8.3.2) and microdiffraction (Beamline 12.3.2) to further analyze the crystal orientations and strains in the teeth.

>Read more on the ALS website

Image: (extract) PIC maps acquired at the tips of four different parrotfish teeth show that they consist of 100-nm-wide, microns-long crystals, bundled into “fibers” interwoven like warp and weft fibers in fabric. These fibers gradually decrease in average diameter from 5 μm at the back of a tooth to 2 μm at the tip. Intriguingly, this decrease in size is spatially correlated with an increase in hardness and stiffness. The orientation angle of the crystals is color-coded (chart at bottom).

 

Research on the teeth of a prehistoric fetus

It gives us information about the last months of a mother and child, who lived 27.000 years BP.

Fossil records enable a detailed reconstruction of our planet’s history and of the evolution of our species. Dental enamel is a sort of biological archive that constantly tracks periods of good and bad health, while forming. Prenatal enamel, which grows during intrauterine life, reports the mother’s history as well.

We have studied fossil records found in the “Ostuni 1” burial site, discovered in Santa Maria di Agnano in Puglia in 1991 by Donato Coppola (Università di Bari, Italy) and dated back over 27,000 years. More specifically, we were interested in the teeth of a fetus found in the pelvic area of the skeleton of a young girl. By analysing the still forming teeth of the baby, it has been possible to obtain information about the health condition of the mother during the last months of pregnancy, to establish the gestational age of the fetus, and also to identify some specificities of the embryonal development. For the first time, it has been possible to reconstruct life and death of an ancient fetus and, at the same time, to shed light on its mother’s health.

Three still-forming incisors, belonging to the fetus, have been visualized and analyzed by means of X-ray microtomography at Elettra. The preliminary analysis on a portion of the fetal mandible, realized at the TomoLab laboratory allowed us to study the still-forming incisor contained within it (see Fig. 1). Thanks to the unique properties of synchrotron radiation and using a specifically-developed methodology, a high resolution 3D analysis has been carried out on the teeth at the SYRMEP beamline. This approach, allowed us to carry out a virtual histological analysis of the precious fossil teeth, revealing the finest structures of the dental enamel in a non-destructive way.

>Read more on the Elettra website

Image:  Pseudo color rendering of the virtual histological section of the Ostuni1b’s upper left deciduous central incisor. The corresponding CT scan has been acquired at the SYRMEP beamline in phase-contras mode.

A first look at how miniscule bubbles affect the texture of noodles

The texture of a noodle is a remarkably complicated thing. When you bite into a spoonful of ramen noodles, you expect a bit of springiness (or a resistance to your bite) on the outside and a pleasantly soft give on the interior. These variations are so tiny as to be often overlooked, but they matter to noodle quality.

There are many factors in play in making a good noodle. For a wheat noodle, the structure of the gluten affects the overall quality. How a noodle dough is stretched, folded, and rolled out matters. And in between all of this, there are miniscule air bubbles that are part of the mix and influence texture.

Until recently, no one had ever looked at the bubbles in noodle dough.

“There was absolutely nothing in the literature indicating that the bubbles were there or that they were important at all. We did have some indirect evidence for bubbles from our ultrasonic experiments, but CLS (Canadian Light Source) microtomography was in some ways a hail Mary experiment: OK, let’s just sheet some dough and see what we find,” said Martin Scanlon, U of M professor in the Faculty of Agriculture and Food Sciences, and the project’s lead researcher.

>Read more on the Canadian Light Source website

 

Apply for the Kai Siegbahn prize 2018

The Prize was established in 2009 in honour of Kai Siegbahn, founder of Nuclear Instruments and Methods A (NIMA), who had a strong and lasting commitment to advancing synchrotron radiation science.

The Editorial Board of NIMA is currently accepting nominations for the 2018 award, and we are counting on you to help us identify potential honorees! We invite you to review the award criteria, and to nominate a worthy colleague.

All nominations should be submitted to the Committee Chair by March 31 2018:

Prof. Fulvio Parmigiani, Kai Siegbahn Chair
Department of Physics, University of Trieste
International Faculty, University of Cologne,
Elettra Sincrotrone Trieste S.C.p.A.
Email: fulvio.parmigiani@elettra.trieste.it

Nomination criteria:

The Prize aims to recognize and encourage outstanding experimental achievements in synchrotron radiation research with a significant component of instrument development. Particular preference will be given to the development of synchrotron radiation spectroscopies.

Rules and eligibility:

Nominations are open to scientists of all nationalities without regard to the geographical site at which the work was performed. Usually, the prize shall be awarded to one person but it may be shared if all recipients have contributed to the same accomplishment. The prize recipient should be 45 years old or younger at the time of selection.

Nominations are accepted from the NIMA advisory board, the NIMA board of editors, synchrotron radiation facility directors as well as from scientists engaged in synchrotron radiation science. Nomination packages should include a nominating letter, at least one supporting letter, a list of five papers on which the award is based as well as a proposed citation for the award.

Atomic Flaws Create Surprising, High-Efficiency UV LED Materials

Subtle surface defects increase UV light emission in greener, more cost-effective LED and catalyst materials

Light-emitting diodes (LEDs) traditionally demand atomic perfection to optimize efficiency. On the nanoscale, where structures span just billionths of a meter, defects should be avoided at all costs—until now.

A team of scientists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Stony Brook University has discovered that subtle imperfections can dramatically increase the efficiency and ultraviolet (UV) light output of certain LED materials.

“The results are surprising and completely counterintuitive,” said Brookhaven Lab scientist Mingzhao Liu, the senior author on the study. “These almost imperceptible flaws, which turned out to be missing oxygen in the surface of zinc oxide nanowires, actually enhance performance. This revelation may inspire new nanomaterial designs far beyond LEDs that would otherwise have been reflexively dismissed.”

>Read more on the NSLS-II website

Image: The research team, front to back and left to right: Danhua Yan, Mingzhao Liu, Klaus Attenkoffer, Jiajie Cen, Dario Stacciola, Wenrui Zhang, Jerzy Sadowski, Eli Stavitski.

 

Liquid crystal molecules form nano rings

Quantised self-assembly enables design of materials with novel properties

At DESY’s X-ray source PETRA III, scientists have investigated an intriguing form of self-assembly in liquid crystals: When the liquid crystals are filled into cylindrical nanopores and heated, their molecules form ordered rings as they cool – a condition that otherwise does not naturally occur in the material. This behavior allows nanomaterials with new optical and electrical properties, as the team led by Patrick Huber from Hamburg University of Technology (TUHH) reports in the journal Physical Review Letters.

The scientists had studied a special form of liquid crystals that are composed of disc-shaped molecules called discotic liquid crystals. In these materials, the disk molecules can form high, electrically conductive pillars by themselves, stacking up like coins. The researchers filled discotic liquid crystals in nanopores in a silicate glass. The cylindrical pores had a diameter of only 17 nanometers (millionths of a millimeter) and a depth of 0.36 millimeters.

There, the liquid crystals were heated to around 100 degrees Celsius and then cooled slowly. The initially disorganised disk molecules formed concentric rings arranged like round curved columns. Starting from the edge of the pore, one ring after the other gradually formed with decreasing temperature until at about 70 degrees Celsius the entire cross section of the pore was filled with concentric rings. Upon reheating, the rings gradually disappeared again.

>Read more on the PETRA III at Desy website

Image: Stepwise self-organisation of the cooling liquid crystals. (Extract, see the entire image here)
Credit: A. Zantop/M. Mazza/K. Sentker/P. Huber, Max-Planck Institut für Dynamik und Selbstorganisation/Technische Universität Hamburg; Quantized Self-Assembly of Discotic Rings in a Liquid Crystal Confined in Nanopores, Physical Review Letters, 2018; CC BY 4.

 

40-year controversy in solid-state physics resolved

An international team at BESSY II headed by Prof. Oliver Rader has shown that the puzzling properties of samarium hexaboride do not stem from the material being a topological insulator, as it had been proposed to be.

Theoretical and initial experimental work had previously indicated that this material, which becomes a Kondo insulator at very low temperatures, also possessed the properties of a topological insulator. The team has now published a compelling alternative explanation in Nature Communications, however.

Samarium hexaboride is a dark solid with metallic properties at room temperature. It hosts Samarium, an element having several electrons confined to localized f orbitals in which they interact strongly with one another. The lower the temperature, the more apparent these interactions become. SmB6 becomes what is known as a Kondo insulator, named after Jun Kondo who was first able to explain this quantum effect.

In spite of Kondo-Effect: some conductivity remains

About forty years ago, physicists observed that SmB6 still retained remnant conductivity at temperatures below 4 kelvin, the cause of which had remained unclear until today. After the discovery of the topological-insulator class of materials around 12 years ago, hypotheses grew insistent that SmB6 could be a topological insulator as well as being Kondo insulator, which might explain the conductivity anomaly at a very fundamental level, since this causes particular conductive states at the surface. Initial experiments actually pointed toward this.

>Read more on the Bessy II website

Image: Electrons with differing energies are emitted along various crystal axes in the interior of the sample as well as from the surface. These can be measured with the angular-resolved photoemission station (ARPES) at BESSY II. Left image shows the sample temperature at 25 K, right at only 1 K. The energy distribution of the conducting and valence band electrons can be derived from these data. The surface remains conductive at very low temperature (1 K).
Credit: Helmholtz Zentrum Berlin

Kilian Peter Heeg wins ESRF Young Scientist award

Kilian Peter Heeg has been awarded the title of Young Scientist 2018 by the ESRF User Organisation in recognition of his pioneering work on light-matter interactions enabling resonant brilliance enhancement of X-ray pulses. This award is presented every year at the ESRF annual User Meeting to a scientist aged 37 or younger for outstanding work conducted at the ESRF.

Kilian Heeg is a physicist and postdoctoral researcher at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Aged just 31, Kilian has already significantly shaped the field of X-ray quantum optics.

Kilian says: “I wanted to be a mathematician when I was a child and I was always fascinated by natural sciences. However in my final years in school I fell in love with physics and very quickly became fascinated with quantum mechanics and especially quantum optics. I feel very honoured and pleased to have been chosen as the winner of this year’s ESRF Young Scientist Award.”

>Read more on the ESRF website

Image: Kilian on ESRF’s ID18 beamline
Credit: ESRF/C. Argoud

The power of Metal-Organic Frameworks

Trapping nuclear waste at the molecular level

Nuclear power currently supplies just over 10% of the world’s electricity. However one factor hindering its wider implementation is the confinement of dangerous substances produced during the nuclear waste disposal process. One such bi-product of the disposal process is airborne radioactive iodine that, if ingested, poses a significant health risk to humans.  The need for a high capacity, stable iodine store that has a minimised system volume is apparent – and this collaborative research project may have found a solution.

Researchers have successfully used ultra-stable MOFs to confine large amounts of iodine to an exceptionally dense area. A number of complementary experimental techniques, including measurements taken at Diamond Light Source and ISIS Neutron and Muon Source, were coupled with theoretical modelling to understand the interaction of iodine within the MOF pores at the molecular level.

High resolution x-ray powder diffraction (PXRD) data were collected at Diamond’s I11 beamline. The stability and evolution of the MOF pore was monitored as the iodine was loaded into the structure. Comparison of the loaded and empty samples revealed the framework not only adsorbed but retained the iodine within its structure.

>Read more on the Diamond Light Source website

Illustration: Airborne radioactive iodine is one of the bi-products of the nuclear waste disposal process. A recent study involving Diamond Light Source and ISIS Neutron and Muon Source showed how MOFs can capture and store iodine which may have implications for the future confinement of these hazardous substances.

Extreme-ultraviolet vortices from a free-electron laser

Extreme-ultraviolet vortices may be exploited to steer the magnetic properties of nanoparticles, increase the resolution in microscopy, and gain insight into local symmetry and chirality of a material; they might even be used to increase the bandwidth in long-distance space communications. However, in contrast to the generation of vortex beams in the infrared and visible spectral regions, production of intense, extreme-ultraviolet (XUV) and x-ray optical vortices still remains a challenge. Here, we present an in-situ and an ex-situ technique for generating intense, femtosecond, coherent optical vortices with tunable topological charge at a free-electron laser (FEL) in the XUV.

The first method takes advantage of nonlinear harmonic generation in a helical undulator and exploits the fact that such harmonics carry a topological charge of l = n-1, where n is the harmonic number. The experiment was performed at the FERMI FEL. An ultraviolet (250-nm) seed laser was used to energy modulate the electron beam (e-beam) in the first undulator (modulator), as shown in the top panel of Figure 1. The e-beam was then sent through a dispersive section (a four-dipole-magnet chicane), where the energy modulation was transformed into a current-density modulation (bunching) with Fourier components spanning many harmonics of the seed laser frequency. Such a bunched e-beam entered the helical radiator tuned to a fundamental wavelength of 31.2 nm (i.e., the 8th harmonic of the seed), producing coherent light in the XUV. The FEL was operated in the high-gain regime, close to the saturation point. Under these conditions, the interaction between the radiation at the fundamental FEL wavelength and the e-beam induced bunching at the second harmonic (15.6 nm), resulting in emission of coherent XUV vortices carrying unit topological charge (l = 1) at intensities on the order of 10−3 of the fundamental FEL emission; see bottom panel in Figure 1.

>Read more on the FERMI website

Image:
Top: The scheme to generate optical vortices at harmonics (in the present case at the 2nd harmonic) of the fundamental FEL wavelength. The optical vortex is separated from the fundamental FEL emission using a Zr filter.
Bottom: Intensity profile of the generated optical vortex with a topological charge of l =1 (left), and interference with a Gaussian beam revealing the twisted nature of the vortex (right).

 

W2 SLS Slider

The Swiss Light Source (SLS) at the Paul Scherrer Institut is a third-generation synchrotron light source. SLS provides photon beams of high brightness for research in physics, biology and chemistry.

W2 SSRL Slider

The Stanford Synchrotron Radiation Lightsource (SSRL) is one of the pioneering synchrotron facilities in the world, known for outstanding user support, training future generations and important contributions to science and instrumentation. SSRL is an Office of Science User Facility operated for the U.S. Department of Energy by Stanford University.

W2 FERMI Slider

The program of construction and commissioning through user experiments of the FEL source FERMI, the only FEL user facility in the world currently exploiting external seeding to offer intensity, wavelength and line width stability, achieved all of its intended targets in 2017.

W2 NSRRC Slider

Taiwan Light Source (TLS, 1.5 GeV) and Taiwan Photon Source (TPS, 3.0 GeV) are the two synchrotron light sources currently operated by the National Synchrotron Radiation Research Center (NSRRC). There are around 13,000 academic user visits to NSRRC every year; approximately 10% are international.