24 research outputs found
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
(), we
can, nevertheless, determine the character of the mass hierarchy and whether
is very large or very small.Comment: 8 pages, 15 figure
Inhibition of DPP-4 reduces acute mortality after myocardial infarction with restoration of autophagic response in type 2 diabetic rats
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
Faraday Dispersion Function of Disk Galaxies with Axisymmetric Global Magnetic Fields. I.
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