Focused X-ray beam allows high-resolution nanowire strain mapping

A team of researchers from Lund University and Northwestern University in the United States have used the nano focused beam at the NanoMAX beamline to construct a 2D map of the distribution of material strain in individual InP-GaInP heterostructure nanowires. Understanding the strain that forms in heterostructure nanowires is essential for tailoring their electronic properties to applications in electronics and for energy materials.

Semiconductor materials are essential for everything from electronics such as computers and mobile phones to LED-lights and solar cells. Different types of semiconductor materials often need to be combined in a so-called heterostructure to realise the advanced functions required for these devices.

Typically the combination is done by growing layers of one semiconductor material on top of another. However, since the distances between the atoms, the lattice spacing, is different in the different materials, it often leads to mismatch and strain in the materials when they are combined in this way. The mismatch puts a limit on what materials are possible to mix and how thick the layers can be.

Read more on the MAX IV website

Image: NanoMAX at Max IV

A probe of light-harvesting efficiency at the nanoscale

SCIENTIFIC ACHIEVEMENT

Using time-resolved experiments at the Advanced Light Source (ALS), researchers found a way to count electrons moving back and forth across a model interface for photoelectrochemical cells.

SIGNIFICANCE AND IMPACT

The findings provide real-time, nanoscale insight into the efficiency of nanomaterial catalysts that help turn sunlight and water into fuel through artificial photosynthesis.

Solar-fuel tech goes for gold

In the search for clean-energy alternatives to fossil fuels, one promising solution relies on photoelectrochemical (PEC) cells: water-splitting, artificial-photosynthesis devices that turn sunlight and water into solar fuels such as hydrogen. In just a decade, researchers have achieved great progress in the development of PEC systems made of light-absorbing gold nanoparticles (NPs) attached to a semiconductor film of titanium dioxide (TiO2).

Read more on the Advanced Light Source website

Image: Laser pulses were used to excite electrons in gold nanoparticles (AuNPs) on a titanium dioxide (TiO2) substrate. X-ray pulses were used to count the electrons moving between the nanoparticles and the substrate. (Credit: Oliver Gessner/Berkeley Lab)

Accurate temperature snapshots

The first high energy density experiments pave way for future research

What does it take to accurately measure the temperature of a material which remains in a stable condition for just a fleeting nanosecond (one millionth of a second)? Consider using the high energy density (HED) instrument at European XFEL. And this is what an international team of researchers, with lead researchers from SLAC National Accelerator Laboratory, US, Oxford University, UK, and European XFEL, have done. Establishing methods to accurately measure temperatures in rapidly-evolving, transient systems is important for diverse purposes such as developing materials for spacecraft thermal shields, which face extreme changes in temperature and pressure when re-entering the Earth’s atmosphere, or in the study of the interior of giant planets such as Jupiter, Saturn, Uranus and Neptune. 

Read more on the European XFEL website

Image: Ulf Zastrau, Group Leader HED at the Experiment Station. Copyright: Jan Scholzel

Captured in the act: Free Electron Laser sheds light on ultrafast relaxation of superfluid helium nanodroplets

Superfluid He nanodroplets are ideal model systems for studying the photodynamics of weakly-bound nanostructures, both experimentally and theoretically; in most cases, superfluidity results in slow relaxation of energy and angular momentum. Using ultrashort tunable XUV pulses, it is now possible to follow the relaxation dynamics of excited helium nanodroplets in great detail.

The relaxation of photoexcited nanosystems is a fundamental process of light-matter interaction. Depending on the couplings of the internal degrees of freedom, relaxation can be ultrafast, converting electronic energy into atomic motion within a few fs, or slow, if the energy is trapped in a metastable state that decouples from its environment. An international research team from Germany, Spain, Italy, the USA, and the local team at the FERMI free-electron laser (FEL), studied helium nanodroplets resonantly excited by femtosecond extreme-ultraviolet (XUV) pulses from FERMI. The researchers found that, despite their superfluid nature, helium nanodroplets in their lower electronically excited states undergo ultrafast relaxation by forming a void bubble, which eventually bursts at the droplet surface thereby ejecting a single metastable helium atom. These results help understanding how nanoparticles interact with energetic radiation, as happens when single nanoparticles are directly imaged at hard-x-ray FEL facilities.

Read more on the Elettra website

Image: Figure left: Simulated density distribution of a helium nanodroplet shorty after it is excited by an XUV laser pulse (Courtesy by M. Barranco). Figure right: Measured photoelectron spectra showing ultrafast energy relaxation within less than a picosecond.

Nanocrystals arrange themselves to form new lattices

Tiny structure that conducts electricity anisotropically offers foundation for new electronic components

Electronic components such as light-emitting diodes or solar cells can never be too minute. The smaller they are, the less power they consume and the wider the range of possible applications. In order to explore smaller and smaller worlds, scientists are constantly on the lookout for new materials with interesting properties. A research team from the University of Tübingen, working with colleagues at DESY and from Russia, has now made such a discovery.

Three-dimensional lattice of nanocrystals and semiconducting molecules. The precise arrangement of the nanocrystals allows current in the form of electrons (e-) to flow in certain directions. Illustration: University of Tübingen, Andre Maier.The scientists attached semiconducting organic molecules to inorganic nanocrystals to form ordered, three-dimensional lattices that have a uniform superstructure and are electrical conductors. “For the first time ever, we were able to determine a correlation between the conductivity and the direction of electrical transport in such lattices made up of nanocrystals,” said Marcus Scheele from the University of Tübingen, one of the team’s two leaders, adding that this is hugely significant in terms of their use in electronic components.

Read more on the DESY website

Image: Three-dimensional lattice of nanocrystals and semiconduction molecules. The prcise arrangement of the nanocrystals allows current in the form of electrons (e-) to flow in certain directions. Illustration: University of Tübingen, Andre Maier.

X-ray beams help seeing inside future nanoscale electronics

The technological advancement of fourth-generation synchrotrons, pioneered by MAX IV Laboratory, opens research opportunities that were impossible just a few years ago. In a newly published research paper, we get proof of the revolutionary impact that MAX IV’s photons can have for the advancement of nanoelectronics, both in research and for industrial manufacturers.

Thanks to the innovative concept of the multi-band achromats, MAX IV Laboratory has paved the way for fourth-generation synchrotrons and as of now, it is the most brilliant source of X-ray for research. The high coherence and brilliance delivered at MAX IV are giving scientists the tools for performing research previously unachievable in the X-ray spectrum. This potential is highlighted in a new publication centred on investigating innovative non-destructive characterization of embedded nanostructures.

Read more on the MAX IV website

Image: Depiction of the process of nanofocused X-ray beams scattering from a single nanowire transistor. Positively charged particles (+) and negatively charged particles (-) represent charge carriers in a p–n junction (where p–n junction is an interface between p-type and n-type semiconductor materials). Outgoing beams, depicted as white rays, represent scattering from different segments of the device (InAs and GaSb). The bending with arrows represents the strain revealed in the experiment.

Credit: Illustration by Dmitry Dzhigaev, Lund University.

World first for Synchrotron InfraRed Photo-Thermal in Life NanoSciences

Measuring drug-induced molecular changes within a cell at sub-wavelength scale

Synchrotron InfraRed Nanospectroscopy has been used for the first time to measure biomolecular changes induced by a drug (amiodarone) within human cells (macrophages) and localized at 100 nanometre scale, i.e. two orders of magnitude smaller than the IR wavelength used as probe. This was achieved at the Multimode InfraRed Imaging and Micro Spectroscopy (MIRIAM) beamline (B22) at Diamond Light Source, the UK’s national synchrotron facility.

This is a major scientific result in Life Sciences shared by an international team made up of researchers from the School of Cancer and Pharmaceutical Science at Kings College London, the Department of Pharmaceutical Technology and Bio-pharmacy at University of Vienna, and the scientists of the MIRIAM B22 beamline at Diamond.

Read more on the Diamond website

Image: Schematic of Synchrotron photo-thermal IR nano-spectroscopy on mammalian cell at beamline B22.

Beyond graphene: monolayer arsenene observed for the first time

An article recently published in 2D Materials shows the first experimental evidence of the successful formation of arsenene, an analogue of graphene with noteworthy semiconducting properties.

This material shows a great potential for the development of new nanoelectronics. Crucial sample preparation and electron spectroscopy experiments were performed at the Bloch beamline at MAX IV.

The discovery of graphene, the single-layer carbon honeycomb material worth the Nobel Prize in Physics in 2010, surely has had a revolutionary impact on research. It triggered a whole new field of study within two-dimensional (2D) materials. However, its application in developing new 2D electronics has been hindered by its lack on an intrinsic band gap. Researchers therefore started to turn their attention to other elements in the periodic table and set their eyes on group V, to which arsenic belongs.
“The aim of the study was to show that arsenene can be formed. Our article is the first to report this”, says Roger Uhrberg, professor at Linköping University and spokesperson for the Bloch beamline at MAX IV. Arsenene, a single-layer buckled honeycomb structure of arsenic, had been previously predicted by various theoretical studies, but this is the first experimental observation that verifies its existence.

>Read more on the MAX IV website

Image: A view of the Bloch beamline at MAX IV. The Bloch beamline consists of two branchlines, and is dedicated to high resolution photoelectron spectroscopy, encompassing angle-resolved (ARPES), spin resolved (spin-ARPES) and core-level spectroscopy.

Double X-ray vision helps tuberculosis and osteoporosis research

Combination measurement shows distribution of metals in biological samples

With an advanced X-ray combination technique, scientists have traced nanocarriers for tuberculosis drugs within cells with very high precision. The method combines two sophisticated scanning X-ray measurements and can locate minute amounts of various metals in biological samples at very high resolution, as a team around DESY scientist Karolina Stachnik reports in the journal Scientific Reports. To illustrate its versatility, the researchers have also used the combination method to map the calcium content in human bone, an analysis that can benefit osteoporosis research.“Metals play key roles in numerous biological processes, from the oxygen transport in our red blood cells and the mineralisation of bones to the detrimental accumulation of metals in nerve cells as seen in diseases like Alzheimer’s,” explains Stachnik who works in the Center for Free-Electron Laser Science CFEL at DESY. High-energy X-rays make metals light up in fluorescence, a method that is very sensitive even to tiny amounts. “However, the X-ray fluorescence measurements usually do not show the ultrastructure of a cell, for example,” says DESY scientist Alke Meents who led the research. “If you want to exactly locate the metals within your sample, you have to combine the measurements with an imaging technique.” The ultrastructure comprises the details of the cell morphology that are not visible under an optical microscope.

>Read More on the DESY Website

Image: Two agglomerates of antibiotic-loaded iron nanocontainers (red) in a macrophage. Credit: Stachnik et al., „Scientific Reports“, CC BY 4.0

Tuneable self-organisation of liquid crystals in nanopores

Innovative path to novel materials with adaptive electrical and optical properties

A team of researchers has used X-rays from DESY’s research light source PETRA III to explore the amazingly diverse self-organisation of liquid crystals in nanometre-sized pores. The study, led by Patrick Huber from the Hamburg University of Technology (TUHH), shows how liquid crystals arrange themselves in pores of different sizes, exhibiting different electrical and optical properties. These could be of interest for applications such as sensors and novel optical metamaterials, as the group around first author Kathrin Sentker from TUHH reports in the journal Nanoscale. The research, which Huber presented at the annual DESY Users’ Meeting running until this Friday, will be continued within the framework of the planned Centre for Multiscale Materials Systems (CIMMS), in which TUHH, University of Hamburg, Helmholtz-Zentrum Geesthacht and DESY are involved and for which the Hamburg Science Authority has just approved approximately four million euros funding.

The researchers had studied a special liquid crystal material called HAT6 (2,3,6,7,10,11-hexakis(hexyloxy)triphenylene; C54H84O6), whose single molecules are disc-shaped. Below about 70 degrees Celsius, they arrange themselves into a liquid crystal; by heating to about 100 degrees, the order can be broken. The scientists filled this material into pores in an aluminium oxide substrate and cooled it down. The cylindrical pores were 17 to 160 nanometres (millionths of a millimeter) in diameter, 0.1 millimetres long and situated on a regular, hexagonal lattice.

Read more on the PETRA III website

Image: Simulation of the different orders of the liquid crystal, matching the measurements. Simulation: Marco D. Mazza, Max Planck Institute for dynamics and self-organisation and und Loughborough University

Electronics of future: magnetic properties of InSb-Mn

The recent volume of “ACS Nano Letters” presented the results of research conducted at the SOLARIS National Synchrotron Radiation Centre and at the Academic Centre for Materials and Nanotechnology of the University of Science and Technology in Kraków.

The research was led by Dr Katarzyna Hnida-Gut and demonstrated that the magnetic properties of indium antimonide nanowires with an addition of manganese (InSb-Mn) can be controlled by the concentration of the dopants. The ground-breaking aspect of this research was that for the first time in the pulse electrosynthesis process in AAO pores (anodic aluminium oxide) high quality InSb-Mn nanowires were obtained, making use of previously determined optimum conditions for the synthesis of the semiconductor indium antimonide.

Some of the measurements conducted as part of the research project were performed using synchrotron radiation at the SOLARIS Centre in Kraków. Thanks to an experiment conducted on PEEM/XAS beamline, it was possible to determine the local structure in the vicinity of manganese atoms. This allowed for the confirmation of the hypothesis that “the manganese atoms in the studied nanowires form small clusters, such as Mn3. It is precisely these clusters that are the source of the magnetic response at room temperature,” explains Dr. Marcin Sikora, one of the co-authors of the paper.

>Read more on the SOLARIS website

Unravelling the growth mechanism of the coprecipitation of iron oxide nanoparticles

Applications involving iron oxide nanoparticles (IONPs) and nanomaterials in general, are expected to provide solutions to many problems in the fields of healthcare, energy and environment. Magnetic nanoparticles (such as IONPs) have been in the exploratory stage for cancer diagnostic (e.g.in the form of magnetic resonance imaging contrast agents) for more than three decades and treatment (e.g.via hypothermia) in the recent decade. However, success stories are rare, partly due to the limited performance of commercially available nanoparticles, related to the particle quality attributes such as size and shape, polydispersity, crystallinity and surface chemistry. Although today’s literature provides many reports on the synthesis of highly complex nanoparticles with superior properties respect the currently approved products, there seems to be a gap to the application of these materials to fully exploit their enhanced capabilities. This is due, at least partly, to obstacles such as low yield and, most importantly, the robustness and reproducibility of the synthesis method. Hence, detailed studies on nanoparticle formation mechanisms are essential to guarantee that successful syntheses are not a “one-off” but can be performed and reproduced at various research institutions at small to large scales. This work presents such a detailed study, unravelling the growth mechanism of the co-precipitation of IONPs in solution with the aid of synchrotron X-Ray diffraction.

>Read more on the Elettra website

Image: TEM images of the nanoparticles formed after 30 s, 1, 2, 3, 4, 5, 7 and 10 min of reaction.

Analyzing the structural disorder of nanocrystals

Research applies unprecedented technique in Brazil for the investigation of crystalline nanoparticles

The development of faster and more efficient electronic devices, better catalysts for the chemical industry, alternative energy sources, and so many other technologies depends increasingly on the in-depth understanding of the behavior of materials at the nanometer scale.
The properties of particles on this scale may be completely different from the properties of the same material in its macroscopic version. In addition, nanoparticles of different sizes and shapes can have completely different characteristics, even though they are formed by the same material.
The possibility of regulating the optical and electrical properties of nanoparticles by controlling their composition, shapes and sizes opens the door to an immense variety of applications. In this context, nanocrystals – nanometric particles that have a crystalline structure – have attracted great interest.
A crystal is a type of solid whose atoms or molecules are arranged in a well-defined three-dimensional pattern that repeats itself in space on a regular basis. The optical and electrical properties of crystalline materials depend not only on the atoms or molecules that constitute them but also on the way they are distributed. Therefore, defects or impurities present during crystal formation cause a disorder in the crystal structure. The consequent modification in the electronic structure of the crystal can lead to changes in its properties.

>Read more on the Brazilian Light Source Laboratory website
Image: PDF analysis obtained from electron diffraction data for nanocrystals before (ZrNC-Benz) and after ligand exchange (ZrNC-OLA).
Credit: Reprinted with permission from J. Phys. Chem. Lett. 2019, 10, 7, 1471-1476. Copyright 2019 American Chemical Society.

Nanoscale sculpturing leads to unusual packing of nanocubes

Cube-shaped nanoparticles with thick shells of DNA assemble into a never-before-seen 3-D “zigzag” pattern that breaks orientational symmetry; understanding such nanoscale behavior is key to engineering new materials with desired organizations and properties.

From the ancient pyramids to modern buildings, various three-dimensional (3-D) structures have been formed by packing shaped objects together. At the macroscale, the shape of objects is fixed and thus dictates how they can be arranged. For example, bricks attached by mortar retain their elongated rectangular shape. But at the nanoscale, the shape of objects can be modified to some extent when they are coated with organic molecules, such as polymers, surfactants (surface-active agents), and DNA. These molecules essentially create a “soft” shell around otherwise “hard,” or rigid, nano-objects. When the nano-objects pack together, their original shape may not be entirely preserved because the shell is flexible—a kind of nanoscale sculpturing.

Now, a team of scientists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Columbia Engineering has shown that cube-shaped nanoparticles, or nanocubes, coated with single-stranded DNA chains assemble into an unusual “zigzag” arrangement that has never been observed before at the nanoscale or macroscale. Their discovery is reported in the May 17 online issue of Science Advances.

>Read more on the NSLS-II website

Image: Brookhaven Lab scientists Fang Lu (sitting), (left to right, standing) Oleg Gang, Kevin Yager, and Yugang Zhang in an electron microscopy lab at the Center for Functional Nanomaterials. The scientists used electron microscopes to visualize the structure of nanocubes coated with DNA.

A compass pointing West

Researchers at the Paul Scherrer Institute PSI and ETH Zurich have discovered a special phenomenon of magnetism in the nano range.

It enables magnets to be assembled in unusual configurations. This could be used to build computer memories and switches to increase the performance of microprocessors. The results of the work have now been published in the journal Science.
Magnets are characterized by the fact that they have a North pole and a South pole. If two common magnets are held close to each other, opposite poles attract and like poles repel each other. This is why magnetic needles, such as those found in a compass, align themselves in the Earth’s magnetic field so that we can use them to determine the cardinal directions North and South and, derived from this, East and West. In the world that we experience every day with our senses, this rule is correct. However, if you leave the macroscopic world and dive into depths of much smaller dimensions, this changes. Researchers at the Paul Scherrer Institute PSI and the ETH Zurich have now discovered a very special magnetic interaction at the level of nanoscopic structures made of magnetic layers only a few atoms thick.

>Read more on the Swiss Light Source at PSI website

Image: Zhaochu Luo, lead author of the study, in front of a so-called sputter deposition tool. In the apparatus the layers of platinum, cobalt and aluminium oxide are produced. Each layer is only a few nanometers thick. Credit: Paul Scherrer Institute/Mahir Dzambegovic

Unraveling plants resistance to drought

Research investigates the chemical nanostructure of water conducting vessels.

Plant cells are encased in a structure called the cell wall, composed mainly of cellulose and lignin. Among other functions, this wall gives structural stability to the cells and controls the entry of water, minerals and other substances. When they die, the cells leave behind their cell wall, forming different structures that support the plant giving rigidity to the stems and that facilitate the transport of substances from the roots to the leaves and vice versa. One such structure is the xylem: a continuous network of conduits about 100 micrometers in diameter that carries the water absorbed by the roots to the leaves.

When they lose water by transpiration, the leaves generate tension in the water column within the xylem. The pressure difference between the interior and exterior of the conduit causes the molecules to behave as links in a current: when a molecule of water evaporates, the rest of the “current” is pulled up.

>Read more on the Brazilian Synchrotron Light Laboratory at CNPEM website

Image: Schematic figure of the technique of infrared nanospectroscopy.