双奇核172Re高自旋态转动带结构实验研究

利用重离子熔合蒸发反应¹⁴⁹Sm(²⁷Al,4nγ)¹⁷²Re布居了形变双奇核¹⁷²Re的高自旋态,用12套带有BGO反康普顿抑制的高纯锗探测器阵列进行了在束γ实验测量,首次建立了形变双奇核¹⁷²Re由3个转动带构成的高自旋态能级纲图.研究和讨论了3个转动带的结构特征,基于已有的高自旋态核结构知识并通过系统学比较和分析指出它们的准粒子组态分别为πh_11/2⊙νi_13/2,πh_9/2⊙νi_13/2和π1/2^－[541]⊙ν1/2^－[521].发现前两个转动带在自旋小于18.5h时其转动能级呈现反常的旋称劈裂.     

Gold-bead scanning near-field optical microscope with laser-force position control

We have developed a scanning near-field optical microscope with an optically trapped metallic particle that has a small diameter compared to the wavelength of visible light. In this microscope we employed spot illumination to enhance the intensity of light scattered from a probe particle so we could reduce the diameter of the probe particle to 40nm. We detected slight irregularities of the surface of the cover glass near 10-nm depth. Also, we observed gold colloidal particles on the surface of the cover glass.     

Sharp photonic Crystal Defect Modes and Their Response to Ultrashort Optical Pulses

Single photonic crystal defects based on an air-bridge structure were fabricated. We obtained sharp defect modes with quality factors higher than 600 and observed their response to ultrashort optical pulses by utilizing two-photon absorption.     

Measurement Accuracy in Phase-Shifting Point Diffraction Interferometer with Two Optical Fibers

A phase-shifting point diffraction interferometer (PS/PDI) with point sources of two single mode optical fibers has been developed, which will be appropriate for the surface figure measurement of large aperture optics on a sub-nanometer scale. To reduce the measurement error factors, a fiber optic plate (FOP) is used as a projection plane for interference pattern. Errors caused by imperfection of optical alignment, such as position of point sources and tilt of FOP, are minimized by analyzing the measured phase data with an original method. Measurement accuracy in the PS/ PDI is estimated with the interference pattern produced by the two optical fiber sources. If inhomogeneity of the FOP and a systematic error of the PS/PDI are eliminated, the measurement accuracy of the present system is estimated to be less than 4nm P-V and 0.7nm rms, respectively, at a measurement wavelength of 632.8 nm.     

Two-photon-induced laser annealing for enhancement of photoluminescence intensity in ZnSe crystal

We present the finding that photoluminescence intensity in ZnSe crystal is enhanced after exposure to a femtosecond laser beam. After the crystal was illuminated with laser light of 1.04 MW/cm(2) during 300 s, photoluminescence intensity was increased approximately 20%. The region in which photoluminescence intensity was enhanced was localized in the optical axis, because this phenomenon occurred in the two-photon excitation process. It is possible to achieve three-dimensional control of photoluminescence intensity by illumination with laser light.     

Direct observation of dark excitons in micelle-wrapped single-wall carbon nanotubes

We have performed electroabsorption spectroscopy on micelle-wrapped single-wall carbon nanotubes. In semiconducting nanotubes, many oscillating structures composed of the increase and decrease of absorption are observed in the spectra in the region of the first and second absorption bands, E11 and E22. The spectral shape is reproduced mainly by the second-derivative curve of the absorption spectrum, which indicates the presence of nearly degenerate bright and dark excitonic states.     

Coadsorption of water and CO molecules on Ru(0 0 1) at high CO coverages: comparisons with a Ru(0 0 1) electrode surface

The coadsorption of carbon monoxide (CO) and water molecules on a Ru(0 0 1) surface has been studied by infrared spectroscopy, LEED and STM. At high CO coverage phases, a 2×2-(2CO+D₂O) structure was observed on both UHV and electrode surfaces. Electrode potential dependent structures from CO and water adlayers on an electrode surface were reproduced on a UHV surface by controlling molecular orientations of the first layer and second over-layer water molecules. At lower CO coverages, a CO band center showed coverage dependent shift down to 1444 cm⁻¹ due to an electron transfer from a lone pair of a water molecule to CO 2π^*.     

Reduction of ion thermal diffusivity associated with the transition of the radial electric field in neutral-beam-heated plasmas in the large helical device

Recent large helical device experiments revealed that the transition from ion root to electron root occurred for the first time in neutral-beam-heated discharges, where no nonthermal electrons exist. The measured values of the radial electric field were found to be in qualitative agreement with those estimated by neoclassical theory. A clear reduction of ion thermal diffusivity was observed after the mode transition from ion root to electron root as predicted by neoclassical theory when the neoclassical ion loss is more dominant than the anomalous ion loss.