Minoru Danno

New synthesis method of fullerenes using microwave‐induced naphthalene‐nitrogen plasma at atmospheric pressure

A new synthesis method of fullerenes has been investigated for microwave induced naphthalene‐nitrogen plasma at atmospheric pressure using a cylindrical coaxial cavity. The toluene extract solution of soot obtained after discharges showed HPLC peaks with retention times corresponding well to those of C60 and C70. The production of fullerenes was also confirmed by mass‐spectrometric analysis. Gas temperature of nitrogen plasma determined from radiative transitions of N2+ was 3800–5700 K. From a comparison of the gas temperature and the incident microwave power, it was found that the reaction efficiency for fullerenes decreases with the increase in the gas temperature of the plasma and shows a maximum at about 4500 K.

A new helical coupling microwave antenna excited high-power CO/sub 2/ laser using a cylindrical resonant cavity

A new helical coupling antenna which was installed into a cylindrical microwave cavity (2.45 GHz) has been investigated to obtain high-power CO/sub 2/ laser operation. Laser experiments using a system of swirling fast axial gas flow parallel to the beam have been performed. The geometric properties of the helical antenna and the gas flow structures were optimized by using numerical codes analyzing the electric fields and gas flow dynamics. The swirling flow of the laser gas mixtures of CO/sub 2/-N/sub 2/-He=0.7-5-19 was caused in the discharge tube by an 8-slit nozzle. It is shown that the electric field obtained by the proper design of the helical coupling coil yields homogeneous discharges. The maximum output power and the efficiency (RF to laser power conversion ratio) was obtained as 1010 W and 15%, respectively, at a gas pressure of 45 torr and a gas flow rate of 57 kg/h.

Excimer laser photolysis study of NH3 and NO

Photolysis in the NH3‐NO system was studied by using an ArF‐excimer laser. It was found that the concentration of NO decreases during laser irradiation for a mixture of gaseous of NH3 and NO. From a quadrupole‐mass spectroscopic analysis of the gases, the decomposition of NO molecules yields selectively H2O and N2 molecules. The dependence of quantum yield of NO decomposition on the concentration of NH3 shows a maximum at the same concentration as that of NO.

Excimer laser photolysis study of NH3 and SO2 mixtures at 193 nm

Photolysis in the NH3‐SO2 system was studied by using an ArF excimer laser. The concentration of SO2 decreases during an irradiation of a mixture of NH3 and SO2. It was found from a quadrupole‐mass spectroscopic analysis of the photolyzed gases and x‐ray diffraction analysis of the solid products that the conversion of SO2 and NH3 yields S (solid) and (NH4)2SO4.

Excimer laser photolysis study of NH3 in the presence of NO at 193 nm

Excimer laser photolysis has been studied for NH3 and NO mixtures at the wavelength of 193 nm. The amount of decomposition of NO was compared with the incident photon energy. It was found that NO decomposition occurs with a quantum yield of 0.94.