Teruo Hosokawa

Formation of bioorganic compounds in simulated planetary atmospheres by high energy particles or photons

Various types of organic compounds have been detected in Jupiter, Titan, and cometary coma. It is probable that organic compounds were formed in primitive Earth and Mars atmospheres. Cosmic rays and solar UV are believed to be two major energy sources for organic formation in space. We examined energetics of organic formation in simulated planetary atmospheres. Gas mixtures including a C-source (carbon monoxide or methane) and a N-source (nitrogen or ammonia) was irradiated with the followings: High energy protons or electrons from accelerators, gamma-rays from 60Co, UV light from a deuterium lamp, and soft X-rays or UV light from an electron synchrotron. Amino acids were detected in the products of particles, gamma-rays and soft X-rays irradiation from each gas mixture examined. UV light gave, however, no amino acid precursors in the gas mixture of carbon monoxide, nitrogen and nitrogen. It gave only a trace of them in the gas mixture of carbon monoxide, ammonia and water or that of methane, nitrogen and water. Yield of amino acid precursors by photons greatly depended on their wavelength. These results suggest that nitrogen-containing organic compounds like amino acid precursors were formed chiefly with high energy particles, not UV photons, in Titan or primitive Earth/Mars atmospheres where ammonia is not available as a predominant N-source.

Generation and measurement of subpicosecond electron beam pulses

The generation and measurement of subpicosecond electron beam pulses by the transverse-longitudinal combination gate system is described. The temporal property of the pulse gate is analyzed with the help of the longitudinal emittance diagram. Close agreement has been obtained between the calculated pulse width and the observed one which was measured by the Lissajouss figure method. A beam pulse of 0.2 ps (FWHM) was produced.

Gigahertz stroboscopy with the scanning electron microscope

The application of the stroboscopic scanning electron microscope to gigahertz Gunn effect devices is discussed. Two modes of operation, the deflection mode and the bunching mode, are considered. In the bunching mode, using 1.5 ps beam pulses, two-dimensional voltage contrast in a Gunn effect device triggered at 1 GHz has been observed. A powerful technique for a device in pulsed operation is also presented. With this technique, the nonuniform domain propagation in the three-dimensional-structure Gunn device in pulsed operation has been clearly observed. The duty cycle of the pulsed operation has been 4x10(-3).

Abiotic synthesis of amino acids by x-ray irradiation of simple inorganic gases

1–2 keV x-ray irradiation was carried out using a synchrotron radiation source on simulated primitive earth environment: a gas mixture of carbon monoxide, nitrogen, and water at atmospheric pressure. High-speed liquid chromatography of the hydrolyzed product solution detected amino acids. The amount of amino acids increased with the total energy absorbed by the gas molecules, and the antipodal optical isomers were generated in almost equal quantities. These imply that the precursors for amino acids were produced through x-ray-induced photolysis of inorganic molecules followed by recombination and polymerization into bio-organic compounds. These results suggest that prebiotic formation of amino acids is possible in primitive earth atmosphere by x ray as well as cosmic ray.

Two‐dimensional observation of Gunn domains at 1 GHz by picosecond pulse stroboscopic SEM

The high‐field domains in a Gunn‐effect diode triggered at 1 GHz have been studied pictorially with the stroboscopic scanning electron microscope. Y‐modulated images have also been obtained.

Photochemical abiotic synthesis of amino-acid precursors from simulated planetary atmospheres by vacuum ultraviolet light

For the purpose of investigating the photon energy dependence of the photoinduced abiotic synthesis of organic molecules, gas mixtures that simulate typical planetary atmospheres, including a carbon source (CO or CH4), a nitrogen source (N2 or NH3), and H2O, were irradiated with synchrotron radiation through a vacuum-ultraviolet transmitting window. Three kinds of window material, fused silica, synthetic quartz, and MgF2, were used as a high-energy-cutting filter, whose absorption-edge energies are 6.4, 8.1, and 10.5eV, respectively. Three types of gas mixture, Titan-type (CH4–N2–H2O), comet-type (CO–NH3–H2O), and primitive-Earth-type (CO–N2–H2O), were irradiated with vacuum-ultraviolet photons in the three energy ranges. After the irradiation, amino-acid formation yields in the acid-hydrolyzed solution of the product were measured with a high-performance liquid chromatograph method. From the Titan- and comet-type mixtures, amino acids were detected by irradiation with photons lower than 8.1eV. For both m...

Analysis of the high‐field domain dynamics in a planar Gunn diode by using a stroboscopic SEM

An analysis has been made for the high‐field domain dynamics in a planar Gunn diode, based on stroboscopic observations by a scanning electron microscope. The 1‐GHz pulsed electron beam was synchronized with the microwave‐triggered oscillating diode. The movement of the domain could be clearly observed. The domain dynamics is discussed in detail, taking the time fluctuation in microwave triggering into account. The experimental results are also supported by a theoretical analysis.

A beamline for photochemical processes at atmospheric pressure.

A beamline especially designed for atmospheric photochemical reactions has been constructed at the NTT synchrotron radiation facility. By inserting a buffer helium chamber with Be and Si(3)N(4) partition windows between the beamline and the reaction chamber, studies can be performed without the differential pumping systems normally used in existing photochemistry beamlines. The reaction chamber is equipped with a gas supply system and analysis systems to investigate gas-phase and surface reactions. Purging using dry purified gases in combination with water-bubbling gives effective control of water concentration in the reaction chamber.

Synchrotron-radiation-induced formation of salt particles on an X-ray lithography mask.

The suppression and removal of contaminants on X-ray masks are required for the application of X-ray lithography to practical semiconductor production, because contamination is easily transferred to the replicated resist patterns and degrades the LSI patterns. In order to study contamination of a Ta/SiN X-ray mask, its growth process was investigated using an atmospheric reaction chamber and in situ observation apparatus for gases at atmospheric pressure. It was found that the contamination particles were ammonium sulfate and oxalate. The sources of the salt particle were also identified.

Stroboscopic scanning electron microscope to observe two-dimensional and dynamic potential distribution of semiconductor devices

The stroboscopic SEM is very usuful to observe the dynamic voltage contrast image of semiconductor devices at a certain phase of repeating cycles. It consists of the usual SEM and the pulse gate which is inserted between the electron gun and the first condenser lens. The effect which affects the pulse width in the picosecond region is avoided in the design of the pulse gate. The shortest half-width of pulse is 0.2 ps. The spot size at usual pulse operations (several ps - several ns) is smaller than 0.1 µm. Examples of the two-dimensional voltage contrast images are shown in cases of 1 GHz Gunn diode and of a Simple 8 MHz IC.