COSMIC impact: next-gen X-ray microscopy platform now operational

A next-generation X-ray beamline now operating at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) brings together a unique set of capabilities to measure the properties of materials at the nanoscale.

Called COSMIC, for Coherent Scattering and Microscopy, this X-ray beamline at Berkeley Lab’s Berkeley Lab’s Advanced Light Source (ALS) allows scientists to probe working batteries and other active chemical reactions, and to reveal new details about magnetism and correlated electronic materials.
COSMIC has two branches that focus on different types of X-ray experiments: one for X-ray imaging experiments and one for scattering experiments. In both cases, X-rays interact with a sample and are measured in a way that provides, structural, chemical, electronic, or magnetic information about samples.

The beamline is also intended as an important technological bridge toward the planned ALS upgrade, dubbed ALS-U, that would maximize its capabilities.

>Read more on the Advanced Light Source website

Image: X-rays strike a scintillator material at the COSMIC beamline, causing it to glow.
Credit: Simon Morton/Berkeley Lab

Determining the impact of post-conservation corrosion

When King Henry VIII’s flagship, the Mary Rose, sank off Portsmouth in 1545, it took with it 1248 iron cannonballs. Since the excavation of the shipwreck (from 1979-1983), the cannonballs have been conserved in different ways, offering a unique opportunity to study different conservation methods.

Humans have been using iron to make weapons, tools and ceremonial items for more than 20,000 years, but once these objects have been excavated they are at risk from corrosion, which can be accelerated in the presence of chlorine. Each recovered artefact has to be conserved to prevent it from deteriorating in the presence of air and water. Until now, a comparison of the effectiveness of different conservation methods has been hampered by the variable nature of both the artefacts found, and the environment in which they were buried.

>Read more on the Diamond Light Source website

Image: Dr Eleanor Schofield, Dr Giannantonio Cibin and Hayley Simon with iron shot and samples on Diamond’s B18 beamline.
Credit: Diamond Light Source

Possible Path to the Formation of Life’s Building Blocks in Space

Experiments at Berkeley Lab’s Advanced Light Source reveal how a hydrocarbon called pyrene could form near stars

Scientists have used lab experiments to retrace the chemical steps leading to the creation of complex hydrocarbons in space, showing pathways to forming 2-D carbon-based nanostructures in a mix of heated gases.

The latest study, which featured experiments at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), could help explain the presence of pyrene, which is a chemical compound known as a polycyclic aromatic hydrocarbon, and similar compounds in some meteorites.

A team of scientists, including researchers from Berkeley Lab and UC Berkeley, participated in the study, published March 5 in the Nature Astronomy journal. The study was led by scientists at the University of Hawaii at Manoa and also involved theoretical chemists at Florida International University.

>Read more on the Advanced Light Source website

Image: A researcher handles a fragment and a test tube sample of the Murchison meteorite, which has been shown to contain a a variety of hydrocarbons and amino acids, in this photo from a previous, unrelated study at Argonne National Laboratory. Experiments at Berkeley Lab are helping to retrace the chemical steps by which complex hydrocarbons like pyrene could form in the Murchison meteorite and other meteorites.
Credit: Argonne National Laboratory

Converting CO2 into usable energy

Scientists show that single nickel atoms are an efficient, cost-effective catalyst for converting carbon dioxide into useful chemicals.

Imagine if carbon dioxide (CO2) could easily be converted into usable energy. Every time you breathe or drive a motor vehicle, you would produce a key ingredient for generating fuels. Like photosynthesis in plants, we could turn CO2 into molecules that are essential for day-to-day life. Now, scientists are one step closer.

Researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory are part of a scientific collaboration that has identified a new electrocatalyst that efficiently converts CO2 to carbon monoxide (CO), a highly energetic molecule. Their findings were published on Feb. 1 in Energy & Environmental Science.

“There are many ways to use CO,” said Eli Stavitski, a scientist at Brookhaven and an author on the paper. “You can react it with water to produce energy-rich hydrogen gas, or with hydrogen to produce useful chemicals, such as hydrocarbons or alcohols. If there were a sustainable, cost-efficient route to transform CO2 to CO, it would benefit society greatly.”

>Read more on the NSLS-II website

Image: Brookhaven scientists are pictured at NSLS-II beamline 8-ID, where they used ultra-bright x-ray light to “see” the chemical complexity of a new catalytic material. Pictured from left to right are Klaus Attenkofer, Dong Su, Sooyeon Hwang, and Eli Stavitski.

 

Scientists confirm speculation on the chemistry of a high-performance battery

X-ray experiments at Berkeley Lab reveal what’s at work in an unconventional electrode.

Scientists have discovered a novel chemical state of the element manganese. This chemical state, first proposed about 90 years ago, enables a high-performance, low-cost sodium-ion battery that could quickly and efficiently store and distribute energy produced by solar panels and wind turbines across the electrical grid.

This direct proof of a previously unconfirmed charge state in a manganese-containing battery component could inspire new avenues of exploration for battery innovations.

X-ray experiments at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) were key in the discovery. The study results were published Feb. 28 in the journal Nature Communications.

Scientists at Berkeley Lab and New York University participated in the study, which was led by researchers at Natron Energy, formerly Alveo Energy, a Santa Clara, California-based battery technology company.

The battery that Natron Energy supplied for the study features an unconventional design for an anode, which is one of its two electrodes. Compared with the relatively mature designs of anodes used in lithium-ion batteries, anodes for sodium-ion batteries remain an active focus of R&D.

>Read more on the Advanced Light Source website

Photo: An array of solar panels and windmills.
Credit: PxHere

Unraveling the Complexities of Auto-Oxidation

A comparison of the etch mechanisms of germanium and silicon

Time multiplexed, deep reactive ion etching (DRIE) is a standard silicon microfabrication technique for fabricating MEMS sensors, actuators, and more recently in CMOS development for 2.5D and 3D memory devices.

At CHESS, we have adopted this microfabrication technique to develop novel x-ray optics called,Collimating Channel Arrays  (CCAs) [1], for confocal x-ray fluorescence microscopy (CXRF). Because the first CCA optics were fabricated from silicon substrates, the range of x-ray fluorescence energies for which they could be used, and hence the elements they could be used to study, was limited. Unwanted x-rays above about 11 keV could penetrate through the silicon, showing up as background and interfering with the measurement.

To solve the background problem, germanium substrates were used to fabricate the CCA optics. Germanium, which is much denser and therefore x-ray opaque than silicon, is also etch compatible with the fluorine etch chemistry for silicon DRIE. However, small differences in etch behavior between germanium and silicon can cause big differences in the outcome. Here, Genova et al JVST B [2] report a systematic comparison of  the etch mechanisms of silicon and germanium, performed with the Plasma Therm Versaline deep silicon etcher at the Cornell NanoScale Science & Technology Facility (CNF). The etch rates of silicon and germanium were compared by varying critical parameters in the DRIE process, especially the applied power and voltage used for each of 3 steps in the etch process,  on custom-designed wafers with a variety of features with systematically varying dimensions.

>Read more on the CHESS website

Image: (extract, full image here) SEM of high aspect ratio (>13:1) etched features in Si at 3.7 μm/min (a) and Ge at 3.4 μm/min (b)

High coherence and intensity at FERMI enables new X-ray interfacial probe

Interfaces are involved in a wide range of systems and have significant implications in many fields of scientific and technological advancement, often determining device performance or chemical reactivity. Vital examples include solar cells, protein folding, and computer chips. A class of commonly used surface science techniques are comprised of even-ordered nonlinear spectroscopies (i.e., second harmonic and sum frequency generation) which exhibit no response in centrosymmetric media due to symmetry constraints.As a result, they have been widely used at optical wavelengths to explore physical and chemical properties of interfaces, where centrosymmetry is broken. Extending this to x-ray wavelengths would effectively combine the element specificity and spectral sensitivity of x-ray spectroscopy with the rigorous interfacial/surface specificity of optical even-ordered nonlinear spectroscopies. Unfortunately, at hard x-ray energies (x-ray wavelength order of the spacing between atoms) these even-ordered nonlinear spectroscopies are effectively bulk probes, as each individual atom breaks inversion symmetry. As soft x-ray wavelengths fall in between the UV and hard x-ray regimes, there has been uncertainty regarding the interface specificity of soft x-ray second harmonic generation.

>Read more on the FERMI webpage

Figure: (extract)  Experimental Design. X-ray pulses are passed through a 2 mm iris and focused onto the graphite sample at normal incidence. The transmitted beam is then passed through a 600 nm aluminum filter and onto a spectrometer grating, spatially resolving the second harmonic signal from the fundamental. Inset: A schematic energy level diagram of the second harmonic generation process. (entire figure here)

 

Magnetic trick triples the power of SLAC’s X-ray laser

The new technique will allow researchers to observe ultrafast chemical processes previously undetectable at the atomic scale.

Scientists at the Department of Energy’s SLAC National Accelerator Laboratory have discovered a way to triple the amount of power generated by the world’s most powerful X-ray laser. The new technique, developed at SLAC’s Linac Coherent Light Source (LCLS), will enable researchers to observe the atomic structure of molecules and ultrafast chemical processes that were previously undetectable at the atomic scale.

The results, published in a Jan. 3 study in Physical Review Letters (PRL), will help address long-standing mysteries about photosynthesis and other fundamental chemical processes in biology, medicine and materials science, according to the researchers.

“LCLS produces the world’s most powerful X-ray pulses, which scientists use to create movies of atoms and molecules in action,” said Marc Guetg, a research associate at SLAC and lead author of the PRL study. “Our new technique triples the power of these short pulses, enabling higher contrast.”

>Read more on the LCSL website

Picture: The research team, from left: back row, Yuantao Ding, Matt Gibbs, Nora Norvell, Alex Saad, Uwe Bergmann, Zhirong Huang; front row, Marc Guetg and Timothy Maxwell.
Credit: Dawn Harmer/SLAC

 

Molecular dynamics on the femtosecond timescale

A photochemical reaction in its becoming has been observed with unprecedented detail at the Free Electron Laser FERMI in Trieste.

The result of the experiment published in Nature Communications paves the way for investigations that can shed new light on photochemical processes.

“Shooting the movie” of a photochemical reaction, interpreting its hidden details with the help of a computer: this is what has been done, thanks to the extraordinary capabilities of the FERMI free electron laser source in Trieste, by a research team composed of the Universities of Uppsala and Gothenburg in Sweden, the Institut Ruđer Bošković of Zagreb, the Elettra-FERMI Laboratory, the University of Trieste and the Laboratory of Physical Chemistry, Matter and Radiation in Paris. The study was published in Nature Communications.

The researchers wanted to capture the details of a chemical reaction promoted by the absorption of light (photochemical process), to understand how the excitation generated by a light beam induces changes on a target molecule. The first steps in a photochemical process involve changes in the electronic and geometric structure of a molecule over extremely short times measured in femtoseconds (1 fs = 10-15 s), which had so far hindered the accurate reconstruction of the entire sequence of the reaction.

The combination of intensity, energy resolution and very short pulse duration of the FERMI seeded free-electron laser source can now for the first time provide exceptionally detailed information on photoexcitation-deexcitation and fragmentation processes of isolated molecules in pump-probe experiments on the 50-femtosecond time scale.

Photoelectron spectroscopy with high resolution in energy and time, combined with accurate electronic structure and molecular dynamics calculations, has allowed to visualize in its entirety the temporal evolution of the prototype system chosen for the experiment: acetylacetone—a stable molecule used in environmental and medical applications.

“Besides revealing the dynamics of the reaction—explains Maria Novella Piancastelli of the University of Uppsala, principal investigator—a strong point of the experiment lies in the general applicability of the method, which leads us to consider it as the best way to investigate fundamental photochemical processes such as photosynthesis, photovoltaic energy production and vision.  The stairway that goes from simple to complex molecules, and from the understanding of phenomena to practical applications is of course a long one, and we are specifically interested in its ‘first step’.

>Read more on the FERMI website

Figure: A pictorial representation of the potential energy surfaces involved in the relaxation mechanism of acetylacetone: the ground state S0 (darker blue), two singlet S2 (ππ*) (light blue) and S1 (nπ*) (orange), and two triplet T2 (nπ*) (light green) and T1 (ππ*) (green) states. This approach based on high-resolution valence spectra backed by high-level calculations is the ultimate way to shed light on fundamental, basic photo processes such as photosynthesis, photovoltaic energy production, and vision.

 

 

Prehistoric Iranian glass under synchrotron light

Scientists from University of Isfahan in Iran have analysed in the ALBA Synchrotron how were made ancient Iranian glass objects that date back to 2.500 BC. These decorative glass pieces were excavated from the ziggurat of Chogha-Zanbil, a type of stepped pyramidal monument, inscribed on the UNESCO World Heritage List.

Ziggurats, the most distinct architectural feature of the Mesopotamian, are a type of massive stone structure built thousand years ago as a temple where deities lived. Nevertheless, Chogha-Zanbil, near Susa (Iran), is one of the few existent ziggurats found outside the Mesopotamian area. During ancient times Chogha-Zanbil was known as Dur Untaš, and may had been a sacred city of the Elamite Kingdom, an ancient Pre-Iranian civilization centred in the far West and Southwest of what is now modern-day Iran.

In order to determine the chemical composition of these unique samples, including one piece of ceramics and one piece of metallurgical crucible, a team of Iranian scientists came to ALBA Synchrotron to analyse them using X-Rays Powder Diffraction at the MSPD beamline. The MSPD analyses were carried out on more than 100 points on the glass objects. Synchrotron light enabled them to obtain high resolution diffraction patterns, from whose interpretation researchers have deduced the exact composition of the clay based structure as well as glassy part of the samples.

>Read more on the ALBA website

Image: The glass objects were originally used at the walls and doors of the tempel Chogha-Zanbil.
Credit: Mohammadamin Emami

Fuel from the sun: insight into electrode performance

Soft x-ray studies of hematite electrodes—potentially key components in producing fuel from sunlight—revealed the material’s electronic band positions under realistic operating conditions.

In photosynthesis, plants use sunlight to split water into oxygen and hydrogen. The oxygen is released into the atmosphere, and the hydrogen is used to produce molecules—such as carbohydrates and sugars—that store energy in chemical bonds. Such compounds constitute the original feedstocks for subsequent forms of fuel consumed by society.

Photoelectrochemical (PEC) water splitting is a form of “artificial” photosynthesis that uses semiconductor material, rather than organic plant material, to facilitate water splitting. Electrodes made of semiconductor material are immersed in an electrolyte, with sunlight driving the water-splitting process. The performance of such PEC devices is largely determined at the interface between the photoanode (the electrode at which light gets absorbed) and the electrolyte.

>Read more on the ALS webpage

Photo: Roy Kaltschmidt

Complex tessellations, extraordinary materials

Simple organic molecules form complex materials through self-organisation

An international team of researchers lead by the Technical University of Munich (TUM) has discovered a reaction path that produces exotic layers with semiregular structures. These kinds of materials are interesting because they frequently possess extraordinary properties. In the process, simple organic molecules are converted to larger units which form the complex, semiregular patterns. With experiments at BESSY II at Helmholtz-Zentrum Berlin this could be observed in detail.

Only a few basic geometric shapes lend themselves to covering a surface without overlaps or gaps using uniformly shaped tiles: triangles, rectangles and hexagons. Considerably more and significantly more complex regular patterns are possible with two or more tile shapes. These are so-called Archimedean tessellations or tilings.

Materials can also exhibit tiling characteristics. These structures are often associated with very special properties, for example unusual electrical conductivity, special light reflectivity or extreme mechanical strength. But, producing such materials is difficult. It requires large molecular building blocks that are not compatible with traditional manufacturing processes.

 

>Read more on the Bessy II website

Image: The new building block (left, red outline) comprises two modified starting molecules connected to each other by a silver atom (blue). This leads to complex, semiregular tessellations (right, microscope image).
Credit: Klappenberger and Zhang / TUM

Structure and Catalytic Activity of Copper Nanoparticles

Research investigates the addition of ceria on the activity of catalysts for the water-gas shift reaction

Catalysts are substances that promote and accelerate chemical reactions without being consumed during the process and are widely used in industrial processes to produce various chemicals.

Catalysts based on copper nanoparticles dispersed in an oxide support benefit various reactions, such as the synthesis of methanol, the alcohol dehydrogenation, or the water gas shift (WGS) reaction which is one of the main processes for hydrogen production on an industrial scale. In this reaction, carbon monoxide reacts with water to produce carbon dioxide CO2 and hydrogen gas H2.

>Read more on the LNLS website

Figure 1: Correlation between the bond length of CuO and the catalyst turnover frequency (TOF) for the catalysts analyzed under WGS conditions with different proportions of copper and ceria.

 

Pigments in Oil Paintings Linked to Artwork Degradation

Scientists have observed how lithium moves inside individual nanoparticles that make up batteries.

The finding could help companies develop batteries that charge faster and last longer. Experts have long known that as oil paintings age, soaps can form within the paint, degrading the appearance of the artworks. The process significantly complicates the preservation of oil paintings—and cultural manifestations, which the paintings themselves help to preserve.

“These soaps may form protrusions that grow within the paint and break up through the surface, creating a bumpy texture,” said Silvia Centeno, a member of the Department of Scientific Research at the New York Metropolitan Museum of Art (The Met). “In other cases, the soaps can increase the transparency of the paint, or form a disfiguring, white crust on the painting.”

Scientists do not understand why the soaps take on different manifestations, and for many years, the underlying mechanisms of how the soaps form remained a mystery.

“The Met, alongside our colleagues from other institutions, is trying to figure out why the process takes place, what triggers it, and if there’s a way we can prevent it,” Centeno said.

 

>Read more on the NSLS-II website

Picture: Scientists from Brookhaven Lab and The Met used beamline 5-ID at NSLS-II to analyze a microscopic sample of a 15th century oil painting. Pictured from left to right are Karen Chen-Wiegart (Stony Brook University/BNL), Silvia Centeno (The Met), Juergen Thieme (BNL), and Garth Williams (BNL).

 

 

 

Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how important bioinorganic electron transfer systems operate. Using a combination of very different, time-resolved measurement methods at DESY’s X-ray source PETRA III and other facilities, the scientists were able to show that so-called pre-distorted states can speed up photochemical reactions or make them possible in the first place. The group headed by Sonja Herres-Pawlis from the RWTH Aachen University  Michael Rübhausen from the University of Hamburg and Wolfgang Zinth from Munich’s Ludwig Maximilian University, is presenting its findings in the journal Nature Chemistry.

The scientists had studied the pre-distorted, “entatic” state using a model system. An entatic state is the term used by chemists to refer to the configuration of a molecule in which the normal arrangement of the atoms is modified by external binding partners such that the energy threshold for the desired reaction is lowered, resulting in a higher speed of reaction. One example of this is the metalloprotein plastocyanin, which has a copper atom at its centre and is responsible for important steps in the transfer of electrons during photosynthesis. Depending on its oxidation state, the copper atom either prefers a planar configuration, in which all the surrounding atoms are arranged in the same plane (planar geometry), or a tetrahedral arrangement of the neighbouring ligands. However the binding partner in the protein forces the copper atom to adopt a sort of intermediate arrangement. This highly distorted tetrahedron allows a very rapid shift between the two oxidation states of the copper atom.

>Read more on the PETRA III website

Image Caption: Entatic state model complexes optimize the energies of starting and final configuration to enable fast reaction rates (illustrated by the hilly ground). The work demonstrates that the entatic state principle can be used to tune the photochemistry of copper complexes.
Credit: RWTH Aachen, Sonja Herres-Pawlis