Development of dual-probe atomic force microscopy system using optical beam deflection sensors with obliquely incident laser beams

We developed a dual-probe (DP) atomic force microscopy (AFM) system that has two independently controlled probes. The deflection of each cantilever is measured by the optical beam deflection (OBD) method. In order to keep a large space over the two probes for an objective lens with a large numerical aperture, we employed the OBD sensors with obliquely incident laser beams. In this paper, we describe the details of our developed DP-AFM system, including analysis of the sensitivity of the OBD sensor for detection of the cantilever deflection. We also describe a method to eliminate the crosstalk caused by the vertical translation of the cantilever. In addition, we demonstrate simultaneous topographic imaging of a test sample by the two probes and surface potential measurement on an α-sexithiophene (α-6T) thin film by one probe while electrical charges were injected by the other probe.     

Effect of MnOx/TiO2 Oxidation State on Ozone Concentration in a Nonthermal Plasma-Driven Catalysis Reactor

Manganese oxides on titanium dioxide were prepared by impregnation method at various calcination temperatures and by deposition-precipitation method and the catalysts were characterized using TG-DTA, XRD, XPS, and N₂ adsorption. Various oxidation states for manganese were obtained and activity towards ozone decomposition inside a nonthermal plasma catalysis reactor was investigated. Activity tests show that with increasing manganese oxidation state, the greater the degree of ozone decomposition inside the reactor. MnOx/TiO₂ prepared by impregnation method calcined at 350 °C showed the highest decrease in ozone concentration.     

Three-dimensional rainbow schlieren measurements in underexpanded sonic jets from axisymmetric convergent nozzles

The rainbow schlieren deflectometry has been combined with the computed tomography to obtain three-dimensional density fields of shock containing free jets and we call the method the schlieren CT. Experiments on the schlieren CT have been performed at a nozzle pressure ratio of 4.0 by using an axisymmetric convergent nozzle with an inner diameter of 10 mm at the exit where the nozzle was operated at an underexpanded condition. Multidirectional rainbow schlieren pictures of an underexpanded sonic jet can be acquired by rotating the nozzle about its longitudinal axis in equal angular intervals and the three-dimensional density fields are reconstructed by the schlieren CT. The validity of the schlieren CT is verified by a comparison with the density fields reconstructed by the Abel inversion method. As a result, it is found that excellent quantitative agreement is reached between the three-dimensional jet density fields reconstructed from both methods.     

Te concentration dependent photoemission and inverse-photoemission study of FeSe1?xTex

We have characterized the electronic structure of FeSe_1−xTe_x for various x values using soft x-ray photoemission spectroscopy (SXPES), high-resolution photoemission spectroscopy (HRPES) and inverse photoemission spectroscopy (IPES). The SXPES valence band spectral shape shows that the 2 eV feature in FeSe, which was ascribed to the lower Hubbard band in previous theoretical studies, becomes less prominent with increasing x. HRPES exhibits systematic x dependence of the structure near the Fermi level (E_F): its splitting near E_F and filling of the pseudogap in FeSe. IPES shows two features, near E_F and approximately 6 eV above E_F; the former may be related to the Fe 3d states hybridized with chalcogenide p states, while the latter may consist of plane-wave-like and Se d components. In the incident electron energy dependence of IPES, the density of states near E_F for FeSe and FeTe has the Fano lineshape characteristic of resonant behavior. These compounds exhibit different resonance profiles, which may reflect the differences in their electronic structures. By combining the PES and IPES data the on-site Coulomb energy was estimated at 3.5 eV for FeSe.     

Development of silicon wafer packaging technology for deep UV LED

This paper reports a deep‐ultraviolet LED (deep‐UV‐LED) package based on silicon MEMS process technology (Si‐PKG). The package consists of a cavity formed by silicon crystalline anisotropic etching, through‐silicon vias (TSVs) filled with electroplated Cu, bonding metals made of electroplated Ni/AuSn and a quartz lid for hermetic sealing. A deep‐UV LED die is directly mounted in the Si‐PKG by AuSn eutectic bonding without a submount. It has advantages in terms of size, heat dissipation, light utilization efficiency, productivity and cost over conventional AlN ceramic packages. We confirmed a light output of 30 mW and effective reflection on Si (111) cavity slopes in the Si‐PKG. Based on simulation, further improvement of the optical output is expected by optimizing DUV‐LED die mount condition.     

Lessons from Earthquakes in Recent Times and their Effects on the Development of Geotechnology

This paper first reviews the earthquakes that occurred since 1995 and then outlines the significant lessons learnt from disasters. The discussion then goes into the induced development of engineering practices that were triggered by those disasters. It is clear that major development occurred in design philosophies, soil improvement, and facilities for research. The last section of this paper addresses the compound effects of earthquakes and rainfall that may make the extent of the disasters worse.     

Uncooled InAs0.09Sb0.91 photoconductors with cutoff wave- length extended to 11.5 μm

Uncooled InAsSb photoconductors were fabricated. The photoconductors were based on InAs0.05Sb0.95 and InAs0.09Sb0.91 thick epilayers grown on InAs substrates by melt epitaxy (ME). Ge immersion lenses were set on the photoconductors. The cutoff wavelength of InAs0.09Sb0.91 detectors is obviously extended to 11.5 mm, and that of InAs0.05Sb0.95 detectors is 8.3 mm. At room temperature, the peak detectivity of Dλp at wavelength of 6.8 mm and modulation frequency of 1 200 Hz is 1.08×109 cm.Hz1/2.W-1 for InAs0.09Sb0.91 photoconductors, the detectivity D at wavelength of 9 mm is 7.56×108 cm.Hz1/2.W-1, and that at 11 mm is 3.92×108 cm.Hz1/2.W-1. The detectivity of InAs0.09Sb0.91 detectors at the wavelengths longer than 9 mm is about one order of magnitude higher than that of InAs0.05Sb0.95 detectors, which rises from the increase of arsenic (As) composition in InAs0.09Sb0.91 materials.