News from the NNI Community - Research Advances Funded by Agencies Participating in the NNI

Scientists trying to create a new photocathode need to develop a material that meets three different parameters: It has to have high "quantum efficiency"—the ratio of electrons produced per incoming photon; it needs to have low intrinsic emittance, which measures how much the beam may diverge after it is produced; and the photocathode must tolerate conditions less than a perfect vacuum. Researchers from the U.S. Department of Energy's Argonne National Laboratory have demonstrated a new material, called ultrananocrystalline diamond, that has an excellent balance of these parameters.

Researchers from the University of Michigan, Jilin University in China, and the Federal University of São Carlos in Brazil have developed a new drug screening technique that relies on gold nanorods to twist light, so that a red glow can signal whether a medication designed to treat type II diabetes and pancreatic cancer is working. The researchers were able to take advantage of the chirality of a protein marker for these diseases, called islet amyloid polypeptides.  

Researchers at Columbia University have developed a technique that exploits the tunable symmetry of 2D materials for nonlinear optical applications and next-generation optical quantum information processing and computing. With the ability to control symmetry at the atomic-layer limit, the researchers demonstrated precise tuning and giant enhancement of optical second harmonic generation with micro-rotator devices and superlattice structures, respectively. Tunable second harmonic generation from micro-rotators could lead to novel on-chip transducers that couple micromechanical motion to sensitive optical signals by turning mechanical motion into light, which is critical for many sensors and atomic force microscopes.

An international team of researchers led by the University of Michigan has discovered a new path toward sending and receiving information with single photons (elementary particles that make up light). The physicists and engineers used a new kind of semiconductor to create quantum dots arranged like an egg carton, the quantum dots being the pockets in the egg carton. These new semiconductors have the potential to bring quantum devices up to room temperature, rather than the extreme cold of liquid nitrogen or liquid helium.

COSMIC, a multipurpose X-ray instrument at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, has made headway in the scientific community since its launch less than two years ago, with groundbreaking contributions in fields ranging from batteries to biominerals. Its capabilities include world-leading soft X-ray microscopy resolution below 10 nanometers, extreme chemical sensitivity, and the ability to measure nanoscale chemical changes in samples in real time. In two journal articles, scientists highlight some of COSMIC’s existing capabilities, including examples of 8-nanometer resolution achieved in imaging magnetic nanoparticles, as well as the first-ever use of X-ray linear dichroic ptychography, a specialized high-resolution imaging technique that maps the orientations of a crystal present in coral skeletons at 35-nanometer resolution.

The properties of two- dimensional (2D) materials, which are just one or a few atoms thick, can be modified by stacking two layers together and rotating one slightly in relation to the other. This creates what are known as Moire patterns, in which tiny shifts in the alignment of atoms between the two sheets create larger-scale patterns. Now, an international team led by MIT researchers has come up with a way of imaging what goes on at the interfaces between these 2D materials, down to the level of individual atoms, and of correlating the Moire patterns at the 2D-3D boundary.

At the nanoscale, water freezes in various ways, and not all of them are completely understood. A researcher at Yale University has focused on a particularly fast process known as contact freezing, in which a supercooled (below freezing, but unfrozen) liquid droplet in the atmosphere collides with a nucleating particle—that is, a particle that facilitates the freezing of a liquid that comes into contact with it. His team of researchers has demonstrated that the proximity of surfaces is enough to induce freezing, but it happens only when there is a liquid prone to surface freezing.

Physicists from the U.S. Department of Energy’s Princeton Plasma Physics Laboratory have made a discovery that could facilitate production of carbon nanotubes. The physicists produced a model showing that nanoparticle formation depends on several factors and that as the electric current transitions from low-to-high strength, the evaporation rate of the carbon atoms also transitions from low-to-high strength. This finding is important because researchers want to control the evaporation of carbon atoms at a moderate rather than rapid rate when performing experiments and creating nanoparticles for industry.

An international research team led by the University at Buffalo has developed a technique for pairing a magnet with graphene, inducing what they describe as “artificial magnetic texture” in the otherwise nonmagnetic material. This discovery could open the door to spintronic graphene devices, potentially leading to more powerful semiconductors and computers.

In an effort to gauge the full potential of 2D polymers – which have a repeatable, symmetric pattern akin to "chicken wire” – researchers from the U.S. Army and Northeastern University have started to computationally design 2D polymers in the hopes that they may develop a superior alternative to conventional aramid fibers, for applications such as armor and fire-resistant clothing. Through computer simulations, the researchers compared the thermal stability of the 1D polymer Kevlar; a 2D polymer called an amide covalent organic framework, known as amCOF; and a hypothetical 2D polymer designed by the laboratory, called graphamid. The results showed that graphamid could potentially withstand temperatures as high as 700 degrees Celsius, which exceeds the limits of both Kevlar and amCOF.