Parity violation in a single domain of spin-triplet Sr2RuO4 superconductors

We observed an unconventional parity-violating vortex in single domain Sr₂RuO₄ single crystals using a transport measurement. The current–voltage characteristics of submicron Sr₂RuO₄ show that the induced voltage has anomalous components which are even functions of the bias current. The results may suggest that the vortex itself has a helical internal structure characterized by a Hopf invariant (a topological invariant). We also discuss that the hydrodynamics of such a helical vortex causes the parity violation to retain the topological invariant.     

Convenient Preparation of Self-Assembled Monolayers Derived from Calix[4]resorcinarene Derivatives Exhibiting Resistance to Desorption

Crown conformers of O-carboxymethylated calix[4]resorcinarenes (CRA-CMs) bearing four perfluorooctyl- and octylazobenzene residues at the lower rim of the cyclic skeleton were synthesized to investigate the resistance to desorption of CRA-CMs forming self-assembled monolayers on aminosilylated silica substrates and the surface energy photocontrol based on E- to-Z photoisomerization of the azobenzene moiety. In comparison with CRA-CM monolayers on silica substrates, the desorption of CRA-CMs on the aminated substrate was remarkably suppressed even when CRA-CM monolayers were sonicated in polar solvents and even in water. The high desorption-resistance was attributable to multi-point adsorption of CRA-CMs through COOH/NH₂ interactions. UV-Vis spectral studies revealed that CRA-CM substituted with p-octylazobenzene exhibited high E- to-Z photoisomerizability up to 92% in self-assembled monolayers, while less photoisomerizability was observed for CRA-CM bearing p-perfluorooctylazobenzenes due to the steric hindrance of the larger perfluoroalkyl chains. Photoinduced changes of contact angles for water up to 8.3° were observed for a CRA-CM monolayer.     

Precision measurement of neutrino oscillation parameters with KamLAND

The KamLAND experiment has determined a precise value for the neutrino oscillation parameter Deltam21(2) and stringent constraints on theta12. The exposure to nuclear reactor antineutrinos is increased almost fourfold over previous results to 2.44 x 10(32) proton yr due to longer livetime and an enlarged fiducial volume. An undistorted reactor nu[over]e energy spectrum is now rejected at >5sigma. Analysis of the reactor spectrum above the inverse beta decay energy threshold, and including geoneutrinos, gives a best fit at Deltam21(2)=7.58(-0.13)(+0.14)(stat) -0.15+0.15(syst) x 10(-5) eV2 and tan2theta12=0.56(-0.07)+0.10(stat) -0.06+0.10(syst). Local Deltachi2 minima at higher and lower Deltam21(2) are disfavored at >4sigma. Combining with solar neutrino data, we obtain Deltam21(2)=7.59(-0.21)+0.21 x 10(-5) eV2 and tan2theta12=0.47(-0.05)+0.06.     

Holographic Bragg gratings in a photoresponsive cross-linked polymer-liquid-crystal composite

Holographic gratings were in a composite material that comprised a cross-linked polymer with azobenzene side chains and a nematic liquid crystal. Holographic recording was based on the photoinduced alignment of the nematic liquid crystal inside a cell as a result of amplification of the photoreorientation of azobenzene residues. The diffraction efficiency depends on cell thickness and reading angle of the gratings, so this composite material exhibits volume holographic properties with Bragg diffraction.     

Tip-enhanced coherent anti-stokes Raman scattering for vibrational nanoimaging

An electric field enhanced by a metallic nanoprobe has locally induced coherent anti-Stokes Raman scattering (CARS) of adenine molecules in a nanometric DNA network structure. Owing to the third-order nonlinearity, the excitation of the CARS polarization is extremely confined to the end of the tip apex, resulting in a spatial resolution far beyond the diffraction limit of light. Our tip-enhanced CARS microscope visualized the DNA network structure at a specific vibrational frequency (approximately 1337 cm(-1)) corresponding to the ring-breathing mode of diazole of adenine molecules.     

Parametric four-wave mixing in the H2Σ+,H′2Π(v′=0) states of NO

2 Σ⁺,H^′2Π(v^′=0)←X²Π(v^′′=0) two-photon transition of NO, both near-infrared and vacuum ultraviolet radiation were emitted along the laser propagation direction. The analyses of emission and excitation spectra revealed that the parametric four-wave mixing (PFWM) process coexisted with amplified spontaneous emission. Polarization properties of the IR radiation are found to be dependent on the rotational levels. Pressure and laser power behaviors of the generated waves were reported. The mechanism of PFWM was discussed in terms of selection rules of the relevant ro-vibronic transitions. Received: 19 September 1996/Revised version: 27 January 1997     

Command surfaces 14 [1]. Photoregulation of in-plane alignment of a liquid crystal by the photoisomerization of stilbenes chemisorbed on a substrate silica surface

Stilbenes were attached to a quartz surface at their 2-position by silylation through a spacer to determine the capability to regulate an azimuthal alignment of a nematic liquid crystal by irradiation with linearly polarized light. Liquid crystal molecules aligned perpendicular to the direction of polarization plane of the actinic light, just as in the case of surface azobenzenes. The efficiency of the photoregulation was influenced by excitation wavelength and hence related with an E/Z isomeric ratio in a photostationary state. The irradiation with 260 nm polarized light resulting in the E-isomer as a major component in the photostationary state gave better optical quality of a photoaligned texture when compared with 330 nm irradiation, suggesting that the orientation of liquid crystals is induced by the rod-like E-isomer. Discussion was made on the possibility of the role of phenanthrenes, which were formed upon prolonged irradiation, in the liquid crystal photoalignment.     

Command surfaces 15 [1]. Photoregulation of liquid crystal alignment by cinnamoyl residues on a silica surface

The surface of a silica substrate plate was modified with a cinnamate moiety having a triethoxysilyl group at the ortho-position through a spacer. The plate was employed to assemble a cell filled with a nematic liquid crystal and exposed to linearly polarized 259 nm light to obtain homogeneous alignment. The direction of the alignment was perpendicular to an electric vector of the actinic light. On the contrary, the exposure of the cell to polarized light at 330 nm did not result in homogeneous alignment while the actinic light caused the disappearance of the chromophore. This wavelength effect on the azimuthal photoalignment suggests that the surface-assisted liquid crystal orientation is triggered by the reorientation of the E-isomer of the cinnamate group. This is in marked contrast to a proposed mechanism of a photoalignment by a thin film of a poly(vinyl cinnamate) derivative (Schadt et al., 1993, Jpn J. appl. Phys., 31, 2155); homogeneous alignment is induced by the axially selective photodimerization of cinnamate groups.