Douglas V. Keller

The Determination of the Liquid Immiscibility Boundaries of the Lithium-Sodium and Thallium-Selenium Systems by the Liquid Density Method

Abstract The immiscibility boundaries and monotectic temperatures of the lithium-sodium and thallium-selenium systems were determined by techniques using density-temperature and density-composition isotherms. The immiscibility boundary of the lithium-sodium system was found to extend from 10.5 to 96 weight percent sodium at the monotectic temperature, 170°±1°C. The critical solution (consolute) temperature was found to be 306°±1°C. The thallium-rich immiscibility region of the thallium-selenium system has a consolute temperature of 750°±1°C and a monotectic isothermal of 380°±1°C extending over the composition range 0.1–32.9 atom percent selenium. The second immiscibility region in this system was found to have a consolute temperature of 454° ± 1°C and a monotectic isothermal of 201° ± 1°C. The latter extends between the composition limits 77–99.9 atom percent selenium.

Spontaneous fracture of coal

Abstract Examples of the spontaneous fracture of various United States coals using several different solvents with solubility parameters in the range 9–15 ( cal/cm 3 ) 1 2 [ 18.5–30.7 ( J/cm 3 ) 1 2 ] were used to identify a swelling—fracture relation which predicts the final maximum particle size of the reacted coal. The effects of liquid ammonia were of particular concern. The model appears consistent with the observed effects of various liquids, including water, on various coals in bench and pilot-plant scale. A distinct advantage for the unique separation of pyrite or other mineral matter was not observed.

Light amplification by a Cd3P2 cylinder fiber

We have fabricated fibers with an a few nm thick Cd3P2 semiconductor layer at the clear glass core glass cladding boundary. We have measured a gain of approximately 7.1 dB in a 4 mm long piece of this Semiconductor Cylinder Fiber (SCF) at a wavelength of 1550 nm. The fiber section was pumped from the side with a 38 mW laser operating at a wavelength of 980 nm. We have reason to believe that the test wavelength of 1550 nm is near the short wavelength end of about a few hundred nm wide gain curve. The SCFs have applications as broad band Fiber Light Amplifiers.

Mathematical model of the absorption and gain in a Cd3P2 cylinder fiber

A theoretical analysis of the light absorption and gain mechanisms in a Cd 3 P 2 Semiconductor Cylinder Fiber is presented. The results of these calculations are in good agreement with previously published experimental data. Cd 3 P 2 has two direct energy gaps, which both influence the gain mechanism. Pump light can be used to reduce the absorption. Stronger pump light that generates more charge carriers will produce net gain (gain above absorption compensation). The fiber exhibits gain over a very wide light wavelength bandwidth.

Metal cylinder fiber

Light absorption spectrum measurements and the light intensity dependence of the light absorption spectrum of a fiber with a very thin gold film at the glass core glass cladding boundary are presented. The thickness of the gold film is less than the scattering length of electrons in this metal. The absorption spectrum appears to be strongly light intensity dependent. We also observed the mode structure of light propagating through the gold film. Our fabrication process can produce large area very thin metal films that are very difficult to produce by other methods.

Wide band gain and amplified stimulated emission measurements in Cd3P2 cylinder fiber

We have measured a net gain of 19.5 dB in a 4 mm long piece of Cd3P2 Semiconductor Cylinder Fiber (SCF) at a wavelength of 1550 nm. The fiber was pumped from the side with a 100 mW, 832 nm laser. Side pumping is very inefficient since only a small portion of the pump light is absorbed by the very thin, approximately 6.694 nm thick, semiconductor film. However, this pumping arrangement is very convenient and does not require wavelength sensitive input and output couplers. We also measured the absorption spectrum. The absorption spectrum is in good agreement with a theoretical model. The absorption spectrum exhibits a step due to the two direct energy gap conduction bands of the Cd3P2 semiconductor film.