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In the vortex core of slightly overdoped Bi 2 Sr 2 CaCu 2 O x , the electron-and hole-like states have been found to exhibit spatial modulations in anti-phase with each other along the Cu-O bonding direction. Some kind of one-dimensionality has been observed in the vortex core, and it is more clearly seen in differential conductance maps at lower biases below AE9 mV.

BACKGROUND:Accurate detection and monitoring of disease-related biomarkers is important in understanding pathophysiology. We devised a rapid immunoreaction system that uses submicrometer polymercoated fluorescent ferrite (FF) beads containing both ferrites (magnetic iron oxide) and fluorescent europium complexes.

The effect of metal nanostructures prepared by nanosphere lithography on photoluminescence ͑PL͒ properties of silicon nanocrystals ͑Si-ncs͒ is studied. By placing Ag nanotriangles or Au nanovoids on SiO 2 films containing Si-ncs, the PL intensity is enhanced. For the sample having Ag nanotriangles, the largest PL enhancement is obtained when the excitation wavelength coincides with the absorption band of Ag nanotriangles. This suggests that the enhancement of the incident field by surface plasmon polariton ͑SPP͒ excitation is responsible for the PL enhancement. On the other hand, for the sample having Au nanovoids, the PL enhancement is mainly made by the enhancement of effective radiative decay rate of Si-ncs by efficient excitation and scattering of SPPs.

The enhancement of photoluminescence (PL) is demonstrated from silicon nanocrystals (Si-ncs) by strong coupling of excitons to surface plasmon polaritons (SPPs) supported by a Au thin film. SPPs excited via excitons in Si-ncs were Bragg scattered to photons by one- or two-dimensional gratings, and strong and directional PL was obtained. From the angular dependence of PL spectra, dispersion relations of electromagnetic modes involved in the light emission process were obtained. The overall agreement between experimentally obtained and theoretically calculated dispersion relations confirmed that the strong and directional PL is mediated by SPPs. The PL decay rate of Si-ncs increased by placing a Au thin film on top and the wavelength dependence of the rate enhancement agreed well with that of the calculated SPP excitation rate. This suggests that the observed PL enhancement is due to efficient energy transfer from excitons to SPPs followed by efficient scattering of SPPs to photons, resulting in the enhancement of luminescence quantum efficiency.