Mechanical vertical manipulation of selected single atoms by soft nanoindentation using near contact atomic force microscopy

A near contact atomic force microscope operated at low-temperature is used for vertical manipulation of selected single atoms from the Si(111)-(7 x 7) surface. The strong repulsive short-range chemical force interaction between the closest atoms of both tip apex and surface during a soft nanoindentation leads to the removal of a selected silicon atom from its equilibrium position at the surface without additional perturbation of the (7 x 7) unit cell. Deposition of a single atom on a created vacancy at the surface is achieved as well. These manipulation processes are purely mechanical, since neither bias voltage nor voltage pulse is applied between probe and sample. Differences in the mechanical response of the two nonequivalent adatoms of the Si(111)-(7 x 7) with the load applied is also detected.     

Multiple superconducting phases in new heavy fermion superconductor PrOs4Sb12

The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear indication of the presence of two distinct superconducting phases with twofold and fourfold symmetries. We infer that the gap functions in both phases have a point node singularity, in contrast to the familiar line node singularity observed in almost all unconventional superconductors.     

Evidence for unconventional strong-coupling superconductivity in PrOs4Sb12: an Sb nuclear quadrupole resonance study

We report Sb-NQR results which evidence a heavy-fermion (HF) behavior and an unconventional superconducting (SC) property in Pr(Os4Sb12 with T(c)=1.85 K. The temperature (T) dependence of nuclear-spin-lattice-relaxation rate, 1/T(1), and NQR frequency unravel a low-lying crystal-electric-field splitting below T0 approximately 10 K, associated with Pr3+(4f(2))-derived ground state. In the SC state, 1/T(1) shows neither a coherence peak just below T(c) K nor a T3-like power-law behavior observed for anisotropic HF superconductors with the line-node gap. The isotropic energy gap with its size Delta/k(B)=4.8 K seems to open up across T(c) below T(*) approximately 2.3 K. It is surprising that Pr(Os4Sb12 looks like an isotropic HF superconductor-it may indeed argue for Cooper pairing via quadrupolar fluctuations.     

Highly stable gold(III) complex with a hydantoin ligand in alkaline media

A novel gold(III) complex with a monodentate 5,5-dimethylhydantoin ligand, [Au(dmh)4]-, is square planar in geometry, inert and highly stable in alkaline solutions because of soft acid-base interactions, and electrochemically reduced near -0.3 V vs Ag/AgCl to give a gold(0) film with a high current efficiency.     

High-spin states in 190Pt

The level structure of 190Pt has been studied experimentally using the 176Yb (18O, 4n) reaction at beam energies of 88 and 95 MeV. γ-γ-t coincidence measurements were carried out. Based onthe analysis of γ-γ coincidence relationships, the level scheme of 190Pt is extended to high-spin states. A new structure built on the 3413.6 keV 14+ state has been observed, and the vi1-213/2 vh-19/2 vj (j = p3/2 or f5/2) configuration is tentatively assigned to it.     

Quantum efficiency and thermal stability of organic dye vapors

Organic dyes, POPOP, perylene and pyren, in the vapor phase are excited by a N₂ laser. The quantum efficiency is measures as a function of temperature up to 450°C. Optical properties such as the radiative transition probability are also estimated from the experimental results. It is found that the decrease in the vapor density by the thermal dissociation can be neglected during several tens of hours.     

90,91Zr photoproton spectra and the core-excitation model

Photoproton energy spectra have been measured for the ^90,91Zr(γ,P)^89,90Y reactions at an E_γ endpoint energy of 30 MeV, and for the ^90,91Zr,(e, e'p)^89,90Y reactions at a number of different electron beam energies around E_e = 21 MeV. Isotopically enriched target foils of metallic ⁹⁰Zr(97.65%) and ⁹¹Zr(89.2%) were used, and the proton spectra measured at 90°. Prominent proton groups are observed in the ⁹¹Zr spectra, particularly around E_p ≈ 11 MeV, which closely resemble groups produced in the ⁹⁰Zr photoreactions. Moreover, the correlating non-ground state proton groups are being produced in transitions leaving the corresponding ⁸⁹Y, ⁹⁰Y residual nuclei in excited levels which also correlate in energy. These photoproton groups from ⁹⁰Zr have previously been identified as representing T_> strength. A qualitative explanation is proposed in terms of the core-excitation model, in which the structure in the ⁹¹Zr proton spectrum is described as representing dipole $\text{T}{}_{\mathrm{>}}\text{(T =}\text{13}\text{2}\text{)}$ strength formed by coupling the 2d$\text{5}\text{2}$ neutron to dipole T_> (T = 6) excitations of a ⁹⁰Zr core.     

Intensity measurements of extreme ultraviolet radiation from helium plasma by photoelectron spectroscopy

Extreme ultraviolet radiation emitted from He plasma has been studied by means of photoelectron energy analyzer. Relative and absolute intensities of Lyman series of ionized helium have been measured. From these spectral intensities, the electron temperature of the plasma has been estimated at several tens of eV.     

Atomic resolution noncontact atomic force and scanning tunneling microscopy of TiO2(110)-(1 x 1) and - (1 x 2): simultaneous imaging of surface structures and electronic states

We present simultaneous imaging of TiO2(110)-(1 x 1) and - (1 x 2) using noncontact atomic force microscopy (NC-AFM) and scanning tunneling microscopy (STM). The surface topography was imaged under NC-AFM feedback, while the surface electronic states were imaged by STM. The image contrasts of NC-AFM and STM were antiphase in (1 x 1) and in phase in (1 x 2). The uppermost oxygen and Ti atoms underneath were, respectively, imaged by NC-AFM and STM. The NC-AFM image contrast was close to the true surface topography in (1 x 2), but reduced in (1 x 1).