Rotation in an Enantiospecific Self‐Assembled Array of Molecular Raffle Wheels

Tailored nano-spaces can control enantioselective adsorption and molecular motion. We report on the spontaneous assembly of a dynamic system—a rigid kagome network with each pore occupied by a guest molecule—employing solely 2,6-bis(1H-pyrazol-1-yl)pyridine-4-carboxylic acid on Ag(111). The network cavity snugly hosts the chemically modified guest, bestows enantiomorphic adsorption and allows selective rotational motions. Temperature-dependent scanning tunnelling microscopy studies revealed distinct anchoring orientations of the guest unit switching with a 0.95 eV thermal barrier. H-bonding between the guest and the host transiently stabilises the rotating guest, as the flapper on a raffle wheel. Density functional theory investigations unravel the detailed molecular pirouette of the guest and how the energy landscape is determined by H-bond formation and breakage. The origin of the guest\u27s enantiodirected, dynamic anchoring lies in the specific interplay of the kagome network and the silver surface

Supernova Neutrinos, Neutrino Oscillations, and the Mass of the Progenitor Star

We investigate the initial progenitor mass dependence of the early-phase neutrino signal from supernovae taking neutrino oscillations into account. The early-phase analysis has advantages in that it is not affected by the time evolution of the density structure of the star due to shock propagation or whether the remnant is a neutron star or a black hole. The initial mass affects the evolution of the massive star and its presupernova structure, which is important for two reasons when considering the neutrino signal. First, the density profile of the mantle affects the dynamics of neutrino oscillation in supernova. Second, the final iron core structure determines the features of the neutrino burst, i.e., the luminosity and the average energy. We find that both effects are rather small. This is desirable when we try to extract information on neutrino parameters from future supernova-neutrino observations. Although the uncertainty due to the progenitor mass is not small for intermediate $\theta_{13}$ ($10^{-5} \lesssim \sin^{2}{2 \theta_{13}} \lesssim 10^{-3}$), we can, nevertheless, determine the character of the mass hierarchy and whether $\theta_{13}$ is very large or very small.Comment: 8 pages, 15 figure

Electronic States of Pentacene Thin Films at Interfaces with Ionic-Liquid Layers Probed by Photoelectron Yield Spectroscopy

Understanding semiconductor–ionic-liquid (IL) interfaces is essential for achieving high-performance electronic devices. However, it is difficult to analyze the interfacial electronic states, particularly in the highest occupied molecular orbital (HOMO), because the probing depth of conventional photoelectron spectroscopy is limited to ∼1 nm. Here, we employ photoelectron yield spectroscopy to probe the interfacial electronic states of pentacene submonolayer thin films underneath IL layers and investigate the impact of the IL layers on the shapes and energy levels of the HOMO for the pentacene submonolayer thin films. With increasing the thickness of the IL layers, the density of states on the HOMO peak broadened, indicating that the IL layers induced an energetic disorder in the density of states of the pentacene submonolayer thin films. In addition, the peak top energy of the HOMO peak and the ionization energy gradually shifted toward higher energies as the IL thickness increased, which is attributed to the shifts in the vacuum level and the increase in the polarization energy at the interfaces. This work demonstrates that the photoelectron yield spectroscopy (PYS) technique can adequately access the electronic states at heterointerfaces, highlighting its significant potential for application in the interfacial characterization of devices

Magnetic Interactions of Vanadyl Phthalocyanine with Ferromagnetic Iron, Cobalt, and Nickel Surfaces

We have investigated the molecular orientation and magnetic properties of vanadyl phthalocyanine (VOPc) deposited on ferromagnetic Fe, Co, and Ni films, which were epitaxially grown on Cu(001) using X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The results reveal that the VOPc framework lies flat on the surfaces with oxygen-up configurations. The spin of the central V atoms in VOPc is antiferromagnetically coupled with those of Fe or Co atoms in the ferromagnetic surface. In contrast, the magnetic coupling between V and Ni is not effective, exhibiting simple paramagnetism of VOPc