Phys.org June 17, 2024 Biomimetic nanotechnology and self-assembly advances need chirality. There is a need to develop general methods to characterize chiral building blocks at the nanoscale in liquids such as water. An international team of researchers (UK, Italy, USA – University of Nebraska, Pennsylvania State University) observed chiroptical second-harmonic Tyndall scattering effect in high-refractive-index dielectric nanomaterial Si nanohelices. They provided a theoretical analysis that explained the origin of the effect and its direction dependence, resulting from different specific contributions of “electric dipole–magnetic dipole” and “electric dipole–electric quadrupole” coupling tensors. They narrowed down the number of such terms to 8 […]
Tag Archives: Chirality
Researchers create materials with unique combination of stiffness, thermal insulation
Phys.org May 29, 2024 Thermal conductivity and elastic modulus are usually positively correlated in soft materials. A team of researchers in the US (North Carolina State University, Texas A&M University) have shown anomalous correlations of thermal conductivity and elastic modulus in 2D hybrid organic–inorganic perovskites (HOIP) by engineering the molecular interactions between organic cations. By replacing conventional alkyl–alkyl and aryl–aryl type organic interactions with mixed alkyl–aryl interactions, they observed an enhancement in elastic modulus with a reduction in thermal conductivity. The anomalous dependence provided a route to engineer thermal conductivity and elastic modulus independently and a guideline to search for […]
Electrons on the run: On chirality, tunneling and light fields
Phys.org December 23, 2022 Tunnel ionization is of paramount importance in strong-field physics and attoscience. However, the tunneling dynamics and properties of the outgoing electronic wave packets often remain hidden beneath the influence of the subsequent scattering of the released electron onto the ionic potential. An international team of researchers (France, Israel) has characterized the influence of sub-barrier dynamics on the amplitude and phase of the wave packets emerging from the tunnel using chiral molecules, whose photoionization by circularly polarized light produces forward-backward asymmetric electron distributions with respect to the light propagation direction. The asymmetric patterns provided a background-free signature […]
Using light to put a twist on electrons
Science Daily February 26, 2020 Chirality occurs not in the structure of the molecules themselves, but in a kind of patterning in the density of electrons within the material. An international team of researchers (USA – MIT, Carnegie Mellon, Northeastern University, Cornell University, Drexel University, Taiwan, Singapore, Japan) found that while titanium diselenide at room temperature has no chirality to it, as its temperature decreases it reaches a critical point where the balance of right-handed and left-handed electronic configurations gets thrown off and one type begins to dominate. They found that this effect could be controlled and enhanced by shining […]