STXM – Lightsources.org

Soft X-ray Laminography: 3D imaging with powerful contrast mechanisms

2020/01/272020/02/20

Soft X-ray 3D imaging has already been realized at synchrotron radiation sources using either scanning transmission X-ray microscopy (STXM) schemes or tomography-based concepts. However, the maximum accessible sample volume is severely limited by the reduced penetration depth of the lower-energy soft X-ray radiation. This becomes even more of a drawback in the case of flat and extended specimens, which can be found in various fields of nanoscience.

The generalized geometry of laminography, characterized by a tilted axis of rotation concerning the incident X-ray beam resulting in a constant material thickness during rotation, has proven to be particularly suitable for the investigation of laterally extended and thin objects. The combination of soft X-rays and laminography provides the unique potential of bridging the gap between investigations of elaborate nanostructured thin film samples and taking advantage of the characteristic absorption contrast mechanisms in the soft X-ray range.

Image: 3D model constructed from soft X-ray laminography measurements of the front tip of the wing scale from a European peacock butterfly.

Meteorites suggest galvanic origins for martian organic carbon

2019/02/252019/02/26

The nature of carbon on Mars has been the subject of intense research since NASA’s Viking-era missions in the 1970s, due to the link between organic (carbon-containing) molecules and the detection of extraterrestrial life. Analyses of Martian meteorites marked the first confirmation that macromolecular carbon (MMC)—large chains of carbon and hydrogen—are a common occurrence in Mars rocks. More recently, researchers have applied the lessons taken from studies of meteorites to the data being gathered by the Curiosity rover, finding similar MMC signatures on Mars itself. Now, the central question is “what is the synthesis mechanism of this abiotic organic carbon?”

>Read more about on the Advanced Light Source website

Image: A high-resolution transmission electron micrograph (scale bar = 50 nm) of a grain from a Martian meteorite. Reminiscent of a long dinner fork, organic carbon layers were found between the intact “tines.” This texture was created when the volcanic minerals of the Martian rock interacted with a salty brine and became the anode and cathode of a naturally occurring battery in a corrosion reaction. This reaction would then have enough energy—under certain conditions—to synthesize organic carbon.
Credit: Andrew Steele

Rational optimization of organic solar-cell materials

2018/05/222018/06/07

The work suggests a way to quickly identify ideal material mixtures and processing methods, bypassing trial-and-error strategies and minimizing labor-intensive synthesis.

To generate electricity from light, the photoactive layer of an organic solar cell (OSC) must allow the photoexcitation and separation of charges, something that can happen in blends of electron-donating and electron-accepting organic materials. Not surprisingly, such blends have been created in steady succession with the goal of improving device efficiency.

However, there are over a thousand combinations of electron donors and acceptors available for use in OSCs and countless processing variations. The reliance on trial and error to identify the best materials and methods is a serious limitation. A way to predict device efficiency based on easily measurable or derivable parameters would go a long way toward streamlining the process.

Image: (extract) Artistic interpretation of an organic solar-cell mixture containing a blend of polymers and fullerenes. Interactions between these molecules (represented by the interaction parameter, χ) affect the degree of mixing that occurs, which in turn is key to device performance.