State-selective optical near-field resonant ionization spectroscopy of atoms near a dielectric surface

Spin-sensitive optical near-field microscopy and spectroscopy are proposed based on the study on the conserved quantities in optical near-field interactions of atoms with dielectric surfaces. A two-step photoionization spectra of Cs atoms resolving hyperfine structures are demonstrated near a planar dielectric surface by using evanescent waves. These techniques of state/spin-selective excitation and highly sensitive detection, combined with the techniques of optical pumping, will open up possibilities of space- and polarization-sensitive detection of optical near‐fields using atomic probes. This novel method provides us with a useful technique for the observation of polarization nature of the optical near-field and controlling the spin states of mesoscopic electronic systems.     

Development of a method for liquid xenon purification using a cryogenic centrifugal pump

We are developing a new type of photon detector for an experiment to search for muons decaying into a positron and a gamma ray. In this experiment, the photon detector will utilize liquid xenon (Xe) as the scintillation material. Good transparency of the liquid Xe is required in order to gain the highest performance out of the detector. Impurities like water and oxygen must be removed efficiently for this purpose. We have developed a new purification system, dedicated to removing water from liquid Xe, by employing a cryogenic centrifugal pump and molecular sieves. The performance of the system is described in this article.     

Formation of square matrix pores on Al film utilizing focused ion beam milled indent

We successfully fabricated a square pattern of anodic alumina oxide (AAO) template in thin Al film grown on Si substrate utilizing focused ion beam (FIB) milled indent. The pore size and its period of the square matrix were about 50 nm and 100 nm, respectively. We found that the minimum indented depth is required to satisfy the critical electric field which is a vertical component toward downward. In addition, we found that the anodizing voltage plays an important role in determining the pore shape and uniformity. The higher anodizing voltage not only reduces the minimum indent depth that is required to create a matrix array but also improves the uniformity of pore shapes in the matrix array.     

Method-performance studies of notified analytical method for inabenfide

Method-performance studies were conducted for the notified revised analytical method of inabenfide in unpolished rice. Six laboratories analyzed unpolished rice spiked with 0.05 microgram/g of inabenfide in replicate. Mean recovery from rice was 85.0%. Repeatability relative standard deviation value was 4.2% and reproducibility relative standard deviation value was 8.1%. The detection limits were 0.002-0.01 microgram/g.     

CMOS LSI-based multichip flexible neural stimulation device with embedded bulk Pt electrodes

A CMOS LSI-based flexible neural stimulation device application with new fabrication technologies has been developed. The device was designed for application in retinal prosthesis. The device is based on multichip architecture, which enables the LSI-based stimulation device to be flexible. A fabrication process of arrayed bulk Pt electrodes, and a packaging structure of LSI chips with flip-chip bonding technology have been developed. These features provide the fabricated device with a lifetime of ten days in saline solution     

Cosmic plasmas: their research frontiers

Nonthermal particle acceleration is one of the most important topics in the physics of cosmic plasmas. Owing to rapid advances in in situ and remote-sensing observations of these plasmas, much details on acceleration processes are now being accumulated. I will review several topics from these recent observational and theoretical accomplishments and discuss their physical significance.     

Sharpening of CVD diamond coated tools by 0.5−10 keV Ar ion beam

CVD diamond coated tungsten carbide tools have been used for cutting and drilling of soft materials such as aluminum and copper alloys. However, it is very difficult to obtain a tool having a sharp tip of the order of sub-μm by mechanical abrasive polishing methods. Therefore, we applied ion beam processing for sharpening the cutting edge of diamond coated tungsten carbide tools. Result shows that it is possible to obtain a 20-80 nm order tip width of a CVD diamond coated knife processed by a 0.5-10 keV Ar⁺ ion beam, and the sharpening speed of a tip of the knife depends on the ion beam energy. Namely, a tip width of a knife processes by a 1.0 keV Ar⁺ ion beam at an ion dose of 2.7 × 10²⁰ ions/cm² becomes 20 nm, and a tip width of a knife processed by a 10 keV Ar⁺ ion beam at an ion dose of 5.4 × 10¹⁹ ions/cm² becomes 40 nm. However, a facet with an apex angle in the range of 60-100° was formed on the cutting edge of a knife with an initial apex angle of 55°, and we found that the facet angle can be controlled by choosing ion beam energy of 0.5-10 keV. Moreover, results show that the processed knife machined by a 0.5 keV Ar⁺ ion beam has very smooth rake and flank faces, and also has a small line edge roughness of the cutting edge compared to those of the sharpened knife by a 1.0-10 keV Ar⁺ ion beam.     

Preparation and characterization of transparent and conductive thin films of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWNTs), synthesized using the arc-discharge method and the direct-injection-pyrolytic synthesis (DIPS) method, were dispersed in a tetrahydrofuran solution containing propylamine and used to prepare transparent and conductive thin films on PET films using an airbrush technique. The SWNTs were analyzed using vis-near infrared absorption spectroscopy, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. The surface resistivity of the SWNT films on the substrates was measured using a four-point probe conductivity measurement. The results revealed that the purity, length, and proportion of the metallic SWNTs are important factors in decreasing the sheet resistance.