Single-molecule laser nanospectroscopy with micro–electron volt energy resolution

Ways to characterize and control excited states at the single-molecule and atomic levels are needed to exploit excitation-triggered energy-conversion processes. Here, we present a single-molecule spectroscopic method with micro–electron volt energy and submolecular-spatial resolution using laser driving of nanocavity plasmons to induce molecular luminescence in scanning tunneling microscopy. This tunable and monochromatic nanoprobe allows state-selective characterization of the energy levels and linewidths of individual electronic and vibrational quantum states of a single molecule. Moreover, we demonstrate that the energy levels of the states can be finely tuned by using the Stark effect and plasmon-exciton coupling in the tunneling junction. Our technique and findings open a route to the creation of designed energy-converting functions by using tuned energy levels of molecular systems.

Completely dark photons from gravitational particle production during the inflationary era

Starting with the de Broglie-Proca Lagrangian for a massive vector field, we calculate the number density of particles resulting from gravitational particle production (GPP) during inflation, with detailed consideration to the evolution of the number density through the reheating. We find plausible scenarios for the production of dark-photon dark matter of mass in a wide range, as low as a micro-electron volt to 1014 GeV. Gravitational particle production does not depend on any coupling of the dark photon to standard-model particles.

By an eccentric whim of fate or on the centralized schedule from above?

In recent years, with the light hand of three nimble yankees: S.Perlmutter, A.Riess and B.Schmidt - almost the whole world community suddenly sparked with very outlandish for many (and erstwhile unknown) problem of dark energy and dark matter. Whereas for natural philosophers there is nothing mysterious about it. Especially when you consider that multilayer ignored by modern science is inherent not only in habitual biological bodies, but also in crystals (possessing at least two additional sheaths) as well as, possibly, even in some evolutionarily advanced planets. Though, undoubtedly, the bulk of dark matter falls on Universe noosphere. As for dark energy, it is, rather, a kind of epistemological paradox that depends entirely on the position of observing subject. After all, on the periphery of a topologically closed Universe, any sober observer, by and large, won’t just find a single dark erg or even an extra electron-volt. However, besides these two clearly contrived pseudo-riddles, in his article the author also undertakes to solve the genuine disturbing minds cosmic mystery associated with so-called “grande silentium universi”. Well and to what extent he succeeded really in that - it's up for you already to decide, dear colleagues!

An Experimental Study on Irradiated Interface of Silicon

Atomic Force Microscopic (AFM) studies of Mega electron-volt (MeV) ions irradiated silicon surface morphology has been studied to a fluence of 5 x 108 ions/cm2. Interesting features of cracks of 50 nm in depth and 100 nm in width have been observed on the irradiated surface. The features seemed to have been caused by the irradiation-induced stress in the irradiated regions of the target surface. The observed feature of crack seems to be mainly due to the high electronic energy loss of the irradiated ions on the surface that induces the stress in it. It confirms that the coarseness of the microstructure of a material directly affect the mechanical properties.

Practical design and performance of a new merged APPLE-Knot undulator

Constructing vacuum-ultraviolet beamlines at synchrotron radiation facilities with giga-electron volt storage ring results in serious heat load on the beamlines which can reduce their performance. To solve this problem, an APPLE-Knot undulator with eight magnet rows has been built at the Shanghai Synchrotron Radiation Facility and has achieved very good performance. However, its performance in vertical polarization mode is imperfect. Here, a new configuration of a magnet-merged APPLE-Knot undulator that has achieved a better performance is reported.