Recent progress in the chemisorption theory for gas-solid systems is reviewed. The CNDO method, a semi-empirical molecular orbital theory taking Coulomb interactions into account. has been applied with success to the system of H, N, C, 0, or F on a graphite basal (0001) surface. The Anderson model in a theory of dilute alloys has been shown to be powerful in understanding the nature of adsorption bond. The model treats only Coulomb interactions on the adatom and introduces parameters in the expression of mixing interaction between electrons on the adatom and in the metal. The role of the electron interactions in forming adsorption bond has been investigated in detail by the method of configuration interactions. More recently, it has been shown that, in analogy to the Heitler-London scheme, the non-orthogonality of the adatom and solid wave functions leads to an antiferromagnetic exchange interaction between the adatom and the solid, and that the interaction might induce covalent adsorption-bond.
Electrical diagnostics are known as useful means for investigating distributions of density and energy of species existing in high temperature gases. In this paper the results of measurment of various electrical characteristics of combustion flames are given. The flames are formed between a pair of opposing burners which act at the same time as two electrodes. As fuels, city gas premixed with air or oxygen and propane premixed with oxygen are used. The electrical impedance between the burners is measured at frequencies up to 2 MHz and the equivalent C-R network is deduced. Combining these results with the potential distribution, the distribution of resistivity and the typical data for electron density in the flame are obtained. For the purpose of obtaining information about the velocity of carrier particles the transient current is observed by imposing rectangular wave voltages between the electrodes. Lastly, the polar effect and the rectification characteristics are measured for unsymmetrical flame composition imposing D. C. and A. C. voltages of various frequencies between the two burners.
The movable tube flowmeter is based on Newtonian laws of motiom and has the following notable merits: (1) The flow rate is obtained by a theoretical calculation regardless of the viscosity under the sole condition that the velocities are uniform at inlet and outlet ends. (2) The flow rate is obtained regardless of flow direction. (3) The shape of the movable tube is arbitrary except at the inlet and outlet ends. In our experiments, the trial flowmeter is placed in series with a well calibrated oval gear flowmeter. The results of experiments show that the values of the flow rate obtained by the above mentioned flowmeters agree very well with one another.
Experimental study has been made on liquid phase epitaxy of GaAs multiple layers grown by a single process using a sliding boat consisting of two graphite blocks. On the epitaxial layers made by this process, each layer was quite uniform in its thickness, and the surface un-dulation was less than 500 A. Mereover the thickness of each layer was controlled within an error of 0.5μ. By introducing a purging process before growing the high purity n-layer, the electron concentration between 1015_??_1616 cm-3 was controlled to within 20% by the amount of Sn in Ga solution. Moreover, the electron concentration was almost constant in the n-layer, and the transition of the electron concentration between n- and n+-layer was sharp, where no dip in the concentration profile was detected. Millimeter-wave Gunn diodes were made using crystals made by this liquid phase epitaxy. A maximum CW output power of 67mW was obtained at 57 GHz with an efficiency of 3.1%.