Phys.org April 14, 2023 In a usual solar cell, the energy of a single photon is transferred to two free charges in the material. However, a few molecular materials like pentacene are an exception and show conversion of one photon into four charges, instead. This excitation doubling, which is called exciton fission, could be extremely useful for high-efficiency photovoltaics, specifically to upgrade the dominant silicon-based technologies. An international team of researchers (Germany, Canada) used time- and angle-resolved photoemission spectroscopy to observe the primary step of singlet fission in crystalline pentacene. Their results indicated a charge-transfer mediated mechanism with a hybridization […]
Improving alloys: Researchers successfully establish a strong mechanical bond of immiscible iron and magnesium
Phys.org April 17, 2023 Steel is heavy, and scientists are turning to alternatives in the quest to improve the safety and speed of transportation, while simultaneously lessening its environmental footprint. Joining of Mg alloy to steel has received wide attention for design of multi-materials. Researchers in Japan have described joining of immiscible pure iron and pure magnesium (Fe–Mg), as a simplified model, performed by solid metal dealloying (SMD) between Mg and Fe100−xNix interlayers that were preliminary joined to the Fe part by diffusion bonding. SMD formed an Fe–Mg bicontinuous composite with interconnected morphology at the Fe–Mg weld interface. The effect […]
Laser light hybrids control giant currents at ultrafast times
Phys.org April 13, 2023 Spin and valley indices represent the key quantum labels of quasi-particles in a wide class of two-dimensional materials and form the foundational elements of the fields of spintronics and valleytronics. Researchers in Germany have discovered a route to induce and control the flow of spin and valley currents at ultrafast times with specially designed laser pulses, offering a new perspective on the ongoing search for the next generation of information technologies. They showed that femtosecond laser light combining optical frequency circularly polarized pulse and a terahertz (THz) frequency linearly polarized pulse can generate precisely tailored and […]
Lightning Bolt Deposits a Strange Mineral Never Seen on Earth Before
Science Alert April 15, 2023 Phosphate minerals such as those in the apatite group tend to be the dominant forms of phosphorus in minerals on the Earth’s surface. Phosphate can be reduced to phosphides during high-energy events, such as lightning and impacts. An international team of researchers (Italy, USA – University of South Florida) has shown that, in addition to formation of metal phosphides, a new compound was formed by lightning in a fulgurite from New Port Richey, Florida.. A calcium phosphite material, ideally CaHPO3, was found in spherules mainly consisting of iron silicides that formed by lightning-induced fusion of […]
Make creativity part of study programs for scientists-in-training, experts urge
Science Daily April 4, 2023 The rate of scientific innovation appears to be slowing down: despite immense investments, the proportion of individual projects that push science in new directions by breaking with previous understanding has decreased since the 1950s. Some observers have attributed these diminishing returns to the notion that fewer fundamental discoveries remain to be made. According to an international team of researchers (USA – NYU Grossman School of Medicine, Germany) a compelling case can be made for another factor: that the culture of science has gradually transitioned toward a more executive and results-oriented approach. In this fast-paced mode, […]
Mosquito Saliva Can Actually Suppress Our Immune System, Study Finds
Science Alert April 18, 2023 Mosquito transmission of dengue viruses to humans starts with infection of skin resident cells at the biting site. There is great interest in identifying transmission-enhancing factors in mosquito saliva in order to counteract them. An international team of researchers (Singapore, USA – University of Texas, University Virginia, Spain, France) has discovered high levels of the anti-immune subgenomic flaviviral RNA (sfRNA) in dengue virus 2-infected mosquito saliva. They confirmed that sfRNA was present in saliva. They showed that salivary sfRNA was protected in detergent-sensitive compartments. Based on this hypothesis, they visualized viral RNAs in vesicles in […]
New family of wheel-like metallic clusters exhibit unique properties
Phys.org April 14, 2023 Researchers in China isolated a family of polyoxo(alkoxo)lanthanide cluster {Ln15} (Ln = Eu (1), Gd (2), Tb (3)) via a simple hydrolysis reaction of lanthanide metal ions in the presence of tricine ligands. X-ray diffraction analyses revealed that {Ln15} displayed a wheel-like structure with a µ5-chloride anion as a template. Each analog showed distinctive functions based on the different Ln(III) ions. Complexes 1 and 3 in the solid state emitted the characteristic fluorescence of Eu(III) or Tb(III). The fluorescence lifetimes of the 5D0 excited state for 1 and the 5D4 excited state for 3 were tested, […]
Photonic filter separates signals from noise to support future 6G wireless communication
Science Daily April 11, 2023 To achieve high reconfigurability in integrated microwave photonic filters (IMPFs) previous works adopt complicated system structures and modulation formats, which put great pressure on power consumption and controlment, and, therefore, impeded the massive deployment of IMPF. Researchers in China proposed a streamlined architecture for a wideband and highly reconfigurable IMPF on the silicon photonics platform. For various practical filter responses, to avoid complex auxiliary devices and bias drift problems, a phase-modulated flexible sideband cancellation method was employed based on the intensity-consistent single-stage-adjustable cascaded-microring. The IMPF exhibited an operation band extending to millimeter-wave and other extraordinary […]
Physicists discover first transformable nanoscale electronic devices
Phys.org April 17, 2023 Interfaces of van der Waals (vdW) materials, such as graphite and hexagonal boron nitride (hBN), exhibit low friction sliding due to their atomically flat surfaces and weak vdW bonding. An international team of researchers (UC Irvine, Japan) has demonstrated that microfabricated gold also slides with low friction on hBN. This enables the arbitrary post-fabrication repositioning of device features both at ambient conditions and in situ to a measurement cryostat. They demonstrated mechanically reconfigurable vdW devices where device geometry and position are continuously tunable parameters. By fabricating slidable top gates on a graphene-hBN device, they produced a […]
Quantum liquid becomes solid when heated
Phys.org April 18, 2023 Raising the temperature of a material enhances the thermal motion of particles. Such an increase in thermal energy commonly leads to the melting of a solid into a fluid and eventually vaporizes the liquid into a gaseous phase of matter. Studying finite-temperature physics of dipolar quantum fluids, an international team of researchers (Denmark, Austria, Spain) found a surprising deviation from this general phenomenology. They described how heating a dipolar superfluid from near-zero temperatures can induce a phase transition to a supersolid state with a broken translational symmetry. They discussed the observation of this effect in experiments […]