A new algorithm could allow researchers to capture attosecond, multiwavelength images of an object. Illuminating a sample with attosecond x-ray pulses could let researchers image phenomena as fleeting as the rearrangement of electrons during chemical reactions. The uncertainty principle dictates that ultrashort pulses have a broad energy spectrum. However, because focusing different wavelengths typically requires multiple sets of optics, most attempts at attosecond imaging are spectroscopic, ignoring all but one radiation frequency. Now, Jianwei Miao at the University of California, Los Angeles, and colleagues have developed an innovative algorithm that can simultaneously reconstruct multiple images of an object at different wavelengths using attosecond pulses. The method offers a way to take spectroscopic images without the need for sophisticated instruments.
The coronavirus pandemic upended schools in the spring of 2020, sending students and faculty home. This rapidly changed how instructors handled laboratory physics courses. With a NSF RAPID grant, JILA Fellow Heather Lewandowski asked instructors what worked—and what didn’t—as they moved their lab courses online.
Extremely thin films of dielectrics and other materials play vital roles in many types of advanced microelectronics, but their tiny dimensions and atomic make-up can impair mechanical performance.
Now, researchers at the NSF STROBE Science and Technology Center in the U.S. have shown they can characterize the mechanical properties of silicon-carbide films as thin as 5 nm using tabletop sources of extreme ultraviolet laser light—showing them to be far softer than thicker films of the same material (Phys. Rev. Mater., doi: 10.1103/PhysRevMaterials.4.073603).
CU Boulder researchers have used ultra-fast extreme ultraviolet lasers to measure the properties of materials more than 100 times thinner than a human red blood cell. The team, led by scientists at JILA, reported its new feat of wafer-thinness this week in the journal Physical Review Materials. The group’s target, a film just 5 nanometers thick, is the thinnest material that researchers have ever been able to fully probe, said study coauthor Joshua Knobloch. “This is a record-setting study to see how small we could go and how accurate we could be,” said Knobloch, a graduate student at JILA, a partnership between CU Boulder and the National Institute of Standards and Technology (NIST). He added that when things get small, the normal rules of engineering don’t always apply. The group discovered, for example, that some materials seem to get a lot softer the thinner they become.
Many of the life’s elementary processes and material properties are determined by how molecules couple and interact. Until recently, it’s been impossible to see how these molecules interact with each other with a high enough resolution. The Raschke Group has used infrared lasers and a new microscope to get a high-resolution view of molecular coupling in porphyrin nanocrystals.
A team of scientists has developed four-dimensional (the three dimensions of space plus the fourth dimension of time) atomic electron tomography. Tomography is a technique for creating images of cross sections of an object using X-rays or ultrasound. The technique directly images the dynamics of structural changes at the atomic scale during nucleation. Nucleation is the creation of structure in a vapor, solution, or liquid. The scientists found that the nuclei came in a broad range of shapes and sizes and possess a diffuse interface surrounding a stable core. Their observations challenge the long-held classical nucleation theory that posits nucleation begins with the formation of perfectly spherical nuclei that grow after they reach a certain critical size.
Two scientists at the University of Colorado Boulder, Professor Henry Kapteyn and Professor Margaret Murnane, a married couple and partners in physics research, have been awarded the 2020 Benjamin Franklin Medal in Physics by the Franklin Institute. lt is one of several awards given out yearly by the institute. In its 196th year, the Franklin Institute continues to pay tribute to its namesake, Benjamin Franklin, by honoring the greatest minds in science. “The Franklin Institute Awards pay tribute to America’s original scientist, Benjamin Franklin, by honoring the greatest minds in science, engineering, and industry,” said Chris Franklin, chair of the Awards Corporate Committee, in a statement. “We believe in the work the Institution does to inspire a passion for learning about science and technology.” Professor Margret Murnane believes that sharing the honor with her husband is one of the best parts about winning the award.
Scanning atomic electron tomography measurements reveal the 3D local structure around single dopant atoms in 2D transition metal dichalcogenides, providing essential information to investigate and predict their electronic properties.
Scientists develop innovative technique to pinpoint coordinates of single atoms. A UCLA-led research team has produced in unprecedented detail experimental three-dimensional maps of the atoms in a so-called 2D material — matter that isn’t truly two-dimensional but is nearly flat because it’s arranged in extremely thin layers, no more than a few atoms thick. Although 2D-materials–based technologies have not yet been widely used in commercial applications, the materials have been the subject of considerable research interest. In the future, they could be the basis for semiconductors in ever smaller electronics, quantum computer components, more-efficient batteries, or filters capable of extracting freshwater from saltwater.
The American Society of Chemistry (ACS) has announced Naomi S. Ginsberg is a recipient of the 2020 early-career award(link is external) in experimental physical chemistry. She is being recognized “For the development of new time- and space-resolved imaging and spectroscopy methods to study dynamical phenomena in heterogeneous materials”.