What happens in nature in femtoseconds observed in milliseconds?
Category: chemistry – Page 39
Density functional theory’s self-interaction correction falters in transition metals, study finds
Density functional theory (DFT) is a cornerstone tool of modern physics, chemistry, and engineering used to explore the behavior of electrons. While essential in modeling systems with many electrons, it suffers from a well-known flaw called self-interaction error. A recent study has identified a new area where a correction for this error breaks down.
Simplified method for observing electron motion in solids unveiled
The ultrafast dynamics and interactions of electrons in molecules and solids have long remained hidden from direct observation. For some time now, it has been possible to study these quantum-physical processes—for example, during chemical reactions, the conversion of sunlight into electricity in solar cells and elementary processes in quantum computers—in real time with a temporal resolution of a few femtoseconds (quadrillionths of a second) using two-dimensional electronic spectroscopy (2DES).
However, this technique is highly complex. Consequently, it has only been employed by a handful of research groups worldwide to date. Now a German-Italian team led by Prof. Dr. Christoph Lienau from the University of Oldenburg has discovered a way to significantly simplify the experimental implementation of this procedure. “We hope that 2DES will go from being a methodology for experts to a tool that can be widely used,” explains Lienau.
Two doctoral students from Lienau’s Ultrafast Nano-Optics research group, Daniel Timmer and Daniel Lünemann, played a key role in the discovery of the new method. The team has now published a paper in Optica describing the procedure.
Carbon nanotube sensor efficiently measures oxygen in gas mixtures under light
Oxygen is essential for life and a reactive player in many chemical processes. Accordingly, methods that accurately measure oxygen are relevant for numerous industrial and medical applications: They analyze exhaust gases from combustion processes, enable the oxygen-free processing of food and medicines, monitor the oxygen content of the air we breathe or the oxygen saturation in blood.
Oxygen analysis is also playing an increasingly important role in environmental monitoring.
“However, such measurements usually require bulky, power-hungry, and expensive devices that are hardly suitable for mobile applications or continuous outdoor use,” says Máté Bezdek, Professor of Functional Coordination Chemistry at ETH Zurich. His group uses molecular design methods to find new sensors for environmental gases.
Rapid single-particle chemical imaging of nanoplastics by SRS microscopy
The shape is another important morphological feature that matters as a critical aspect of nanotoxicity. Studies have shown that shape plays a role in determining the cellular uptake of micro-nano particles (65, 66). SRS images of plastic particles confirmed the existence of shape diversity for micro-nano plastics in bottled water. To account for the shape of plastic particles in a statistical manner, we measure the aspect ratio of individual particles above the diffraction limit (Fig. 6 H). The aspect ratio is widely acknowledged in nanotoxicology studies (67, 68). The aspect ratio of the plastic particles detected ranges from 1 to 6, and the average aspect ratio for particles is around 1.7. Fig. 6 I–M provides a pictorial view of how the aspect ratio is related to the particle shape. Particles with an aspect ratio of above 3 are most likely to be fibrous in shape, while particles with an aspect ratio of below 1.4 will be largely spherical. Shape variation on plastic particles has been found in all polymers detected, confirming the widely recognized idea that real-world micro-nano plastics have diverse morphological prosperities. This dimension is hard to be resembled by engineered polymer nanoparticles commonly studied in research laboratories, and the toxicological consequences pertaining to real-life plastic particle exposures and their differing physicochemical properties (i.e., size, shape) have yet to be determined.
Machine learning reveals how to dissolve polymeric materials in organic solvents
It’s about my paper.
Dissolving polymers with organic solvents is the essential process in the research and development of polymeric materials, including polymer synthesis, refining, painting, and coating. Now more than ever recycling plastic waste is a particularly imperative part of reducing carbon produced by the materials development processes.
Polymers, in this instance, refer to plastics and plastic-like materials that require certain solvents to be able to effectively dissolve and therefore become recyclable, though it’s not as easy as it sounds. Utilizing Mitsubishi Chemical Group’s (MCG) databank of quantum chemistry calculations, scientists developed a novel machine learning system for determining the miscibility of any given polymer with its solvent candidates, referred to as χ (chi) parameters.
This system has enabled scientists to overcome the limitations arising from a limited amount of experimental data on the polymer-solvent miscibility by integrating massive data produced from the computer experiments using high-throughput quantum chemistry calculations.
Webb reveals unexpected complex chemistry in primordial galaxy
University of Arizona astronomers have learned more about a surprisingly mature galaxy that existed when the universe was just less than 300 million years old—just 2% of its current age.
Observed by NASA’s James Webb Space Telescope, the galaxy—designated JADES-GS-z14-0—is unexpectedly bright and chemically complex for an object from this primordial era, the researchers said. This provides a rare glimpse into the universe’s earliest chapter.
The findings, published in the journal Nature Astronomy, build upon the researchers’ previous discovery, reported in 2024, of JADES-GS-z14-0 as the most distant galaxy ever observed. While the initial discovery established the galaxy’s record-breaking distance and unexpected brightness, this new research delves deeper into its chemical composition and evolutionary state.
Mysterious phenomenon at center of galaxy could reveal new kind of dark matter
A mysterious phenomenon at the center of our galaxy could be the result of a different type of dark matter.
Dark matter, the mysterious form of unobserved matter which could make up 85% of the mass of the known universe, is one of science’s biggest manhunts.
In this first of its kind study, scientists have taken a step closer to understanding the elusive mystery matter. They believe a reimagined candidate for dark matter could be behind unexplained chemical reactions taking place in the Milky Way.