Tag Archives: DESY

Observing photo exposure one nanoscale grain at a time

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A June 9, 2015 news item on Nanotechnology Now highlights research into a common phenomenon, photographic exposure,

Photoinduced chemical reactions are responsible for many fundamental processes and technologies, from energy conversion in nature to micro fabrication by photo-lithography. One process that is known from everyday’s life and can be observed by the naked eye, is the exposure of photographic film. At DESY’s [Deutsches Elektronen-Synchrotron] X-ray light source PETRA III, scientists have now monitored the chemical processes during a photographic exposure at the level of individual nanoscale grains in real-time. The advanced experimental method enables the investigation of a broad variety of chemical and physical processes in materials with millisecond temporal resolution, ranging from phase transitions to crystal growth. The research team lead by Prof. Jianwei (John) Miao from the University of California in Los Angeles and Prof. Tim Salditt from the University of Göttingen report their technique and observations in the journal Nature Materials.

A June 9, 2015 DESY press release (also on EurekAlert), which originated the news item, provides more detail about the research,

The researchers investigated a photographic paper (Kodak linagraph paper Type 2167 or “yellow burn paper”) that is often used to determine the position of the beam at X-ray experiments. “The photographic paper we looked at is not specially designed for X-rays. It works by changing its colour on exposure to light or X-rays,” explains DESY physicist Dr. Michael Sprung, head of the PETRA III beamline P10 where the experiments took place.

The X-rays were not only used to expose the photographic paper, but also to analyse changes of its inner composition at the same time. The paper carries a photosensitive film of a few micrometre thickness, consisting of tiny silver bromide grains dispersed in a gelatine matrix, and with an average size of about 700 nanometres. A nanometre is a millionth of a millimetre. When X-rays impinge onto such a crystalline grain, they are diffracted in a characteristic way, forming a unique pattern on the detector that reveals properties like crystal lattice spacing, chemical composition and orientation. “We could observe individual silver bromide grains within the ‘burn’ paper since the X-ray beam had a size of only 270 by 370 nanometres – smaller than the average grain,” says Salditt, who is a partner of DESY in the construction and operation of the GINIX (Göttingen Instrument for Nano-Imaging with X-Rays) at beamline P10.

The X-ray exposure starts the photolysis from silver bromide to produce silver. An absorbed X-ray photon can create many photolytic silver atoms, which grow and agglomerate at the surface and inside the silver bromide grain. The scientists observed how the silver bromide grains were strained, began to turn in the gelatine matrix and broke up into smaller crystallites as well as the growth of pure silver nano grains. The exceptionally bright beam of PETRA III together with a high-speed detector enabled the ‘filming’ of the process with up to five milliseconds temporal resolution. “We observed, for the first time, grain rotation and lattice deformation during photoinduced chemical reactions,” emphasises Miao. “We were actually surprised how fast some of these single grains rotate,” adds Sprung. “Some spin almost one time every two seconds.”

“As advanced synchrotron light sources are currently under rapid development in the US, Europe and Asia,” the authors anticipate that “in situ X-ray nanodiffraction, which enables to measure atomic resolution diffraction patterns with several millisecond temporal resolution, can be broadly applied to investigate phase transitions, chemical reactions, crystal growth, grain boundary dynamics, lattice expansion, and contraction in materials science, nanoscience, physics, and chemistry.”

Here’s a link to and a citation for the paper,

Grain rotation and lattice deformation during photoinduced chemical reactions revealed by in situ X-ray nanodiffraction by Zhifeng Huang, Matthias Bartels, Rui Xu, Markus Osterhoff, Sebastian Kalbfleisch, Michael Sprung, Akihiro Suzuki, Yukio Takahashi, Thomas N. Blanton, Tim Salditt, & Jianwei Miao. Nature Materials (2015) doi:10.1038/nmat4311 Published online 08 June 2015

This paper is behind a paywall.

Nanoparticles in 3D courtesy of x-rays

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A Feb. 4, 2015 Deutsches Elektronen-Synchrotron (DESY) press release (also on EurekAlert) announces a 3D first,

For the first time, a German-American research team has determined the three-dimensional shape of free-flying silver nanoparticles, using DESY’s X-ray laser FLASH. The tiny particles, hundreds of times smaller than the width of a human hair, were found to exhibit an unexpected variety of shapes, as the physicists from the Technical University (TU) Berlin, the University of Rostock, the SLAC National Accelerator Laboratory in the United States and from DESY report in the scientific journal Nature Communications. Besides this surprise, the results open up new scientific routes, such as direct observation of rapid changes in nanoparticles.

The press release goes on to describe the work in more detail,

“The functionality of nanoparticles is linked to their geometric form, which is often very difficult to determine experimentally,” explains Dr. Ingo Barke from the University of Rostock. “This is particularly challenging when they are present as free particles, that is, in the absence of contact with a surface or a liquid.”

The nanoparticle shape can be revealed from the characteristic way how it scatters X-ray light. Therefore, X-ray sources like DESY’s FLASH enable a sort of super microscope into the nano-world. So far, the spatial structure of nanoparticles has been reconstructed from multiple two-dimensional images, which were taken from different angles. This procedure is uncritical for particles on solid substrates, as the images can be taken from many different angles to uniquely reconstruct their three-dimensional shape.

“Bringing nanoparticles into contact with a surface or a liquid can significantly alter the particles, such that you can no longer see their actual form,” says Dr. Daniela Rupp from the TU Berlin. A free particle, however, can only be measured one time in flight before it either escapes or is destroyed by the intense X-ray light. Therefore, the scientists looked for a way to record the entire structural information of a nanoparticle with a single X-ray laser pulse.

To achieve this goal, the scientists led by Prof. Thomas Möller from the TU Berlin and Prof. Karl-Heinz Meiwes-Broer and Prof. Thomas Fennel from the University of Rostock employed a trick. Instead of taking usual small-angle scattering images, the physicists recorded the scattered X-rays in a wide angular range. “This approach virtually captures the structure from many different angles simultaneously from a single laser shot,” explains Fennel.

The researchers tested this method on free silver nanoparticles with diameters of 50 to 250 nanometres (0.00005 to 0.00025 millimetres). The experiment did not only verify the feasibility of the tricky method, but also uncovered the surprising result that large nanoparticles exhibit a much greater variety of shapes than expected.

The shape of free nanoparticles is a result of different physical principles, particularly the particles’ effort to minimize their energy. Consequently, large particles composed of thousands or millions of atoms often yield predictable shapes, because the atoms can only be arranged in a particular way to obtain an energetically favourable state.

In their experiment, however, the researchers observed numerous highly symmetrical three-dimensional shapes, including several types known as Platonic and Archimedean bodies. Examples include the truncated octahedron (a body consisting of eight regular hexagons and six squares) and the icosahedron (a body made up of twenty equilateral triangles). The latter is actually only favourable for extremely small particles consisting of few atoms, and its occurrence with free particles of this size was previously unknown. “The results show that metallic nanoparticles retain a type of memory of their structure, from the early stages of growth to a yet unexplored size range,” emphasizes Barke.

Due to the large variety of shapes, it was especially important to use a fast computational method so that the researchers were capable of mapping the shape of each individual particle. The scientists used a two-step process: the rough shape was determined first and then refined using more complex simulations on a super computer. This approach turned out to be so efficient that it could not only determine various shapes reliably, but could also differentiate between varying orientations of the same shape.

This new method for determining the three-dimensional shape and orientation of nanoparticles with a single X-ray laser shot opens up a wide spectrum of new research directions. In future projects, particles could be directly “filmed” in three dimensions during growth or during phase changes. “The ability to directly film the reaction of a nanoparticle to an intense flash of X-ray light has been a dream for many physicists – this dream could now come true, even in 3D!,” emphasises Rupp.

The researchers have provided an image showing their work,

Caption: This is a wide-angle X-ray diffraction image of a truncated twinned tetrahedra nanoparticle. Credit: Hannes Hartmann/University of Rostock

Caption: This is a wide-angle X-ray diffraction image of a truncated twinned tetrahedra nanoparticle.
Credit: Hannes Hartmann/University of Rostock

Here’s a link to and a citation for the paper,

The 3D-architecture of individual free ​silver nanoparticles captured by X-ray scattering by Ingo Barke, Hannes Hartmann, Daniela Rupp, Leonie Flückiger, Mario Sauppe, Marcus Adolph, Sebastian Schorb, Christoph Bostedt, Rolf Treusch, Christian Peltz, Stephan Bartling, Thomas Fennel, Karl-Heinz Meiwes-Broer, & Thomas Möller. Nature Communications 6, Article number: 6187 doi:10.1038/ncomms7187 Published 04 February 2015

This article is open access.

Watching buckyballs (buckminsterfullerenes) self-assemble in real-time

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For the 5% or less of the world who need this explanation, the reference to a football later in this post is, in fact, a reference to a soccer ball. Moving on to a Nov. 5, 2014 news item on Nanowerk (Note: A link has been removed),

Using DESY’s ultrabright X-ray source PETRA III, researchers have observed in real-time how football-shaped carbon molecules arrange themselves into ultra-smooth layers. Together with theoretical simulations, the investigation reveals the fundamentals of this growth process for the first time in detail, as the team around Sebastian Bommel (DESY and Humboldt Universität zu Berlin) and Nicola Kleppmann (Technische Universität Berlin) reports in the scientific journal Nature Communications (“Unravelling the multilayer growth of the fullerene C60 in real-time”).

This knowledge will eventually enable scientists to tailor nanostructures from these carbon molecules for certain applications, which play an increasing role in the promising field of plastic electronics. The team consisted of scientists from Humboldt-Universität zu Berlin, Technische Universität Berlin, Universität Tübingen and DESY.

Here’s an image of the self-assembling materials,

Caption: This is an artist's impression of the multilayer growth of buckyballs. Credit: Nicola Kleppmann/TU Berlin

Caption: This is an artist’s impression of the multilayer growth of buckyballs.
Credit: Nicola Kleppmann/TU Berlin

A Nov. 5, 2014 DESY (Deutsches Elektronen-Synchrotron) press release (also on EurekAlert), describes the work further,

The scientists studied so called buckyballs. Buckyballs are spherical molecules, which consist of 60 carbon atoms (C60). Because they are reminiscent of American architect Richard Buckminster Fuller’s geodesic domes, they were christened buckminsterfullerenes or “buckyballs” for short. With their structure of alternating pentagons and hexagons, they also resemble tiny molecular footballs. [emphasis mine]

Using DESY’s X-ray source PETRA III, the researchers observed how buckyballs settle on a substrate from a molecular vapour. In fact, one layer after another, the carbon molecules grow predominantly in islands only one molecule high and barely form tower-like structures..“The first layer is 99% complete before 1% of the second layer is formed,” explains DESY researcher Bommel, who is completing his doctorate in Prof. Stefan Kowarik’s group at the Humboldt Universität zu Berlin. This is how extremely smooth layers form.

“To really observe the growth process in real-time, we needed to measure the surfaces on a molecular level faster than a single layer grows, which takes place in about a minute,” says co-author Dr. Stephan Roth, head of the P03 measuring station, where the experiments were carried out. “X-ray investigations are well suited, as they can trace the growth process in detail.”

“In order to understand the evolution of the surface morphology at the molecular level, we carried out extensive simulations in a non-equilibrium system. These describe the entire growth process of C60 molecules into a lattice structure,” explains Kleppmann, PhD student in Prof. Sabine Klapp’s group at the Institute of Theoretical Physics, Technische Universität Berlin. “Our results provide fundamental insights into the molecular growth processes of a system that forms an important link between the world of atoms and that of colloids.”

Through the combination of experimental observations and theoretical simulations, the scientists determined for the first time three major energy parameters simultaneously for such a system: the binding energy between the football molecules, the so-called “diffusion barrier,” which a molecule must overcome if it wants to move on the surface, and the Ehrlich-Schwoebel barrier, which a molecule must overcome if it lands on an island and wants to hop down from that island.

“With these values, we now really understand for the first time how such nanostructures come into existence,” stresses Bommel. “Using this knowledge, it is conceivable that these structures can selectively be grown in the future: How must I change my temperature and deposition rate parameters so that an island of a particular size will grow. This could, for example, be interesting for organic solar cells, which contain C60.” The researchers intend to explore the growth of other molecular systems in the future using the same methods.

Here’s a link to and a citation for the paper,

Unravelling the multilayer growth of the ​fullerene C60 in real time by S. Bommel, N. Kleppmann, C. Weber, H. Spranger, P. Schäfer, J. Novak, S.V. Roth, F. Schreiber, S.H.L. Klapp, & S. Kowarik. Nature Communications 5, Article number: 5388 doi:10.1038/ncomms6388 Published 05 November 2014

This article is open access.

I was not able to find any videos of these buckyballs assembling in real-time. Presumably, there are technical issues with recording the process, financial issues, or some combination thereof. Still, I can’t help but feel teased (tongue in cheek) by these scientists who give me an artist’s concept instead. Hopefully, budgets and/or technology will allow the rest of us to view this process at some time in the future.

Viewing a photosynthesis subsystem in a near-natural state

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[downloaded from http://www.desy.de/infos__services/presse/pressemeldungen/@@news-view?id=9383]

Molecular structure of photosystem II, which arranges itself in rows. Credit: Martin Bommer/HU Berlin [downloaded from http://www.desy.de/infos__services/presse/pressemeldungen/@@news-view?id=9383]

Apparently, this image represents a near-natural state for a photosynthesis subsystem called, Photosynthesis II. Here’s more from a Nov. 4, 2014 news item on Nanowerk (Note: A link has been removed),

Photosynthesis is one of the most important processes in nature. The complex method with which all green plants harvest sunlight and thereby produce the oxygen in our air is, however, still not fully understood. Researchers using DESY’s X-ray light source PETRA III have examined a photosynthesis subsystem in a near-natural state. According to the scientists led by Privatdozentin Dr. Athina Zouni from the Humboldt University (HU) Berlin, the X-ray experiments on what is known as photosystem II reveal, for example, yet unknown structures. Their results are published in the scientific journal Structure (“Native-like Photosystem II Superstructure at 2.44 Å Resolution through Detergent Extraction from the Protein Crystal”). The technology utilised could also be of interest for analysing other biomolecules.

A Nov. 4, 2014 DESY (Deutsches Elektronen-Synchrotron) press release, which originated the news item, describes some of the issues with studying ‘photosynthetic machinery’,

Photosystem II forms part of the photosynthetic machinery where water, with the help of sunlight, is split into hydrogen and oxygen. As one of the membrane proteins, it sits in the cell membrane. Membrane proteins are a large and vital group of biomolecules that are, for example, important in addressing a variety of medical issues. In order to decode the protein structure and reveal details on how biomolecules function, researchers use the very bright and short-wave X-rays of PETRA III and other similar facilities. Small crystals, however, must initially be grown from these biomolecules.

“The structure of single molecules cannot be directly seen even with the brightest X-rays,” explains co-author and DESY researcher Dr. Anja Burkhardt of Measuring Station P11, where the experiments were carried out. “In a crystal, however, a multitude of these molecules are arranged in a highly symmetrical fashion. Thus the signal, resulting from X-ray diffraction of these molecules, is amplified. The molecular structure can then be calculated from the diffraction images.”

In addition to these difficulties the scientists were also grappling with this problem (from the press release),

Biomolecules – and especially membrane proteins – cannot easily be compelled into crystal form as it is contrary to their natural state. Preparing suitable samples is therefore a crucial step in the whole analysis process. For instance, photosystem II must be first separated from the membrane, where it is bound to numerous small fat molecules (lipids). Researchers use special detergents for this purpose, such as those also principally found in soap. The catch: instead of lipids, the biomolecules are now surrounded by detergents, which may make the crystals spongy under certain conditions, thus exacerbating the analysis.

“What we want is to come as close as possible to nature,” stresses Zouni. The closer the proteins in the crystal are to their natural state, the better the results.

The press release describes how the team solved the problem,

“The trick was to use a detergent that strongly differs from the lipids in composition and structure,” explains the researcher.

Before examining the biomolecular crystals using X-rays, a portion of the water is extracted and replaced by an anti-freeze. The crystals are usually frozen for the experiments because the high-energy X-ray doesn’t damage them so quickly in the frozen state. During this process, the researchers would like to avoid ice formation.

“The dehydration process removed not only the water in our samples, but also completely removed the detergent, something we didn’t expect,” says Zouni.“Our samples are closer to the natural state than what has been reported before.”

Consequently, the investigation’s spatial resolution increased from about 0.6 nanometres (a millionth of a millimetre) to 0.244 nanometres. This is not, in fact, the highest resolution ever achieved in a photosystem II study, but the analysis shows that the photosystem II proteins are arranged within the crystals as pairs of rows, something that also occurs in the natural environment.

This latest development builds on previous research according to the press release,

Electron microscope investigations by Professor Egbert Boekema’s group at the University of Groningen in the Netherlands had already shown the photosystems’ crystal like arrangement in the natural membrane — a kind of tiny solar cell. Electron microscopy could better recognize connections using direct observation of the native membrane while X-ray crystallography could reveal the smallest details.

The press release ends with how the latest work could have an impact on further research,

“We placed the structural data over the electron microscope images – they matched precisely,” says Zouni. The investigation also revealed structures that were invisible before. “We can see exactly where the bonds to the lipids are located,” the scientist explains. The more the researchers discover about photosystem II, the better they understand exactly how it functions.

The procedure of using a new detergent, however, is not only interesting in terms of photosystem II. “The method can potentially be applied to many membrane proteins,” stresses Zouni. In the future, many biomolecules could maybe examined in a more natural state than ever before.

Here’s a link to and a citation for the paper from Zouni’s team,

Native-like Photosystem II Superstructure at 2.44 Å Resolution through Detergent Extraction from the Protein Crystal by Julia Hellmich, Martin Bommer, Anja Burkhardt, Mohamed Ibrahim, Jan Kern, Alke Meents, Frank Müh, Holger Dobbek, and Athina Zouni. Structure Volume 22, Issue 11, p1607–1615, 4 November 2014  DOI: http://dx.doi.org/10.1016/j.str.2014.09.007

This paper is open access.

ETA Nov. 6, 2014: On the off chance the links to the Nanowerk news item or DESY press release do not yield results, you may be able to find the DESY Nov. 5, 2014 news release here on EurekAlert.

Hydrodynamic alignment and assembly of nano-fibrils results in cellulose fibers stronger than both aluminum and steel

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A June 2, 2014 news item on Azonano describes the new fibres (which come from wood),

“Our filaments are stronger than both aluminium and steel per weight,” emphasizes lead author Prof. Fredrik Lundell from the Wallenberg Wood Science Center at the Royal Swedish Institute of Technology KTH in Stockholm. “The real challenge, however, is to make bio based materials with extreme stiffness that can be used in wind turbine blades, for example. With further improvements, in particular increased fibril alignment, this will be possible.”

The June 2, 2014 DESY ( one of the world’s leading accelerator centres) press release describes the research in detail,

A Swedish-German research team has successfully tested a new method for the production of ultra-strong cellulose fibres at DESY’s research light source PETRA III. The novel procedure spins extremely tough filaments from tiny cellulose fibrils by aligning them all in parallel during the production process. …

…

For their method, the researchers took tiny, nanometre-sized cellulose fibrils and fed them together with water through a small channel. Two additional water jets coming in perpendicular from left and right accelerate the fibril flow. “Following the acceleration, all nano fibrils align themselves more or less parallel with the flow,” explains co-author Dr. Stephan Roth from DESY, head of the experimental station P03 at PETRA III where the experiments took place. “Furthermore, salt is added to the outer streams. The salt makes the fibrils attach to each other, thereby locking the structure of the future filament.”

Finally, the wet filaments are left to dry in air where they shrink to form a strong fibre. “Drying takes a few minutes in air,” explains co-author Dr. Daniel Söderberg from KTH. “The resulting material is completely compatible with the biosphere, since the natural structure of the cellulose is maintained in the fibrils. Thus, it is biodegradable and compatible with human tissue.”

The bright X-ray light from PETRA III enabled the scientists to follow the process and check the configuration of the nano fibrils at various stages in the flow. “Research today is driven by cross-disciplanary collaborations,” underlines Söderberg. “Without the excellent competence and possibilities brought into the project by the team of DESY’s experimental station P03 this would not have been possible.”

As the scientists write, their fibres are much stronger than all other previously reported artificial filaments from cellulose nano fibrils. In fact, the artificial filaments can rival the strongest natural cellulose pulp fibres extracted from wood at the same degree of alignment of the nano fibrils. “In principle, we can make very long fibres,” says Lundell. “Up until now we have made samples that where ten centimetres long or so, but that is more of an equipment issue than a fundamental problem.”

For their experiments, the researchers have used nano fibrils extracted from fresh wood. “In principle, it should be possible to obtain fibrils from recycled paper also,” says Lundell. But he cautions: “The potential of recycled material in this context needs further investigations.”

Here’s a link to and a citation for the published paper,

Hydrodynamic alignment and assembly of nano-fibrils resulting in strong cellulose filaments by Karl M. O. Håkansson, Andreas B. Fall, Fredrik Lundell, Shun Yu, Christina Krywka, Stephan V. Roth, Gonzalo Santoro, Mathias Kvick, Lisa Prahl Wittberg, Lars Wågberg & L. Daniel Söderberg. Nature Communications, 2014; DOI: 10.1038/ncomms5018

This is an open access paper.

I posted a June 3, 2014 item on cellulose nanofibriil titled:  Doubling paper strength with nanofibrils; a nanocellulose.

All about time, metronomes, and attoseconds

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Apparently there’s a metronome (the world’s most accurate) which makes it possible to get slow-motion videos/movies of atoms and molecules. The Jan. 16, 2012 news item on Nanowerk offers this,

The world’s most accurate metronome keeps stroke to an incredible 10 quintillionth of a second. The device enables slow-motion pictures from the world of molecules and atoms, scientists from the Center for Free-Electron Laser Science (CFEL) in Hamburg, Germany, and the Massachusetts Institute of Technology (MIT) report. The metronome, an ultrashort pulse laser, acting as an optical flywheel, is currently the most precise clock generator on short time scales, writes the research team headed by DESY scientist Prof. Franz X. Kärtner in the journal Nature Photonics (“Optical flywheels with attosecond jitter”). CFEL is a joint venture of DESY, the German Max Planck Society and the University of Hamburg.

I find this prospect gobsmacking (quite stunning), from the news item,

The accuracy of the laser beat is ten attoseconds (quintillionth of a second), or 0.000 000 000 000 000 01 seconds. [emphasis mine] Atomic clocks achieve a higher precision, yet on longer time scales. Only with this accurate laser beat it is possible to take motion pictures of the nanocosm, as the movement of electrons in molecules and atoms take place on time scales of some 100 attoseconds to femtoseconds. [emphasis mine] “That is about the time an electron needs for orbiting a hydrogen nucleus or for the electric charge to move through a molecule during photosynthesis,” Kärtner explains. With novel light sources, so-called free-electron lasers, researchers expect fundamental new insights into those processes.

I can hardly wait to see my first nanocosm in motion. There’s no word as to when this might be possible in either the news item on Nanowerk or on the Center for Free-Electron Laser Science (CFEL) announcement page.