The solubility of hydrogen sulphide and carbon dioxide, respectively, in 2.5 and 5.0 N aqueous monoethanolamine solutions has been determined at temperatures of 40°C and 100°C. Partial pressures of CO2 ranged from 0.1 to 1000 psia, while partial pressures of H2S ranged from 0.3 to 650 psia. The results have been used, together with literature data, to calculate enthalpies of solution.
The solubility of mixtures of carbon dioxide and hydrogen sulphide in a 2.5 N monoethanolamine solution has been determined at temperatures of 40°C and 100°C. Partial pressures of CO2 ranged from 0.7 to 5630 kPa, while partial pressures of H2S ranged from 0.7 to 3780 kPa. The present results extend the published data on this system which were limited to partial pressures below 200 kPa. The results have been compared with two methods of prediction based upon a thermodynamic model.
The effects of the substrate bias voltage and the deposition temperature on the electrical characteristics and the 1/f noise of TiNx/n-Si Schottky diodes fabricated by reactive magnetron sputtering are investigated. As the substrate bias voltage varies from −40 to −100 V, the ideality factor of the diodes remain almost unchanged whereas the noise intensity as a function of the current shows a shift parallel by about one order of magnitude. At low current levels, the noise intensity is proportional to the current and is attributed to the mobility and diffusivity fluctuation. At higher current levels, the noise intensity is proportional to the square of the current and is attributed to bulk traps mainly near the interface. Analysis of the noise measurements shows that both the Hooge parameter and the bulk trap density near the interface first are increased and then decreased as the negative substrate bias voltage increases from −40 to −100 V. This is in contrast with the effects of the deposition temperature where we found that the Hooge parameter remains almost constant, while both the ideality factor and the interface states density are decreased as the deposition temperature increases from room temperature to 400 °C. The trap properties of the TiNx/n-Si Schottky diodes are correlated with the stoichiometry of the TiNx films investigated by spectroscopic ellipsometry measurements.
We report the photovoltaic properties of the donor-acceptor composite system of poly (p-phenylenevinylene͒ ͑PPV͒ and viologen. We observed the significant enhancement of photocurrent with increasing the doping ratio of viologen. The maximum photocurrent of viologen-doped PPV was nine times as high as that of the pristine PPV. The maximum quantum yield and photosensitivity are 13% ͑electron/photon͒ and 0.05 A/W, respectively, at low bias voltage ͑Ϫ2 V͒. The increase of photocurrent is explained with the efficient charge separation that resulted from the transfer of photoexcited electrons from PPV to viologen. The mixture of PPV and viologen can be used as a sensitive photodiode material.
We compared the structural and optical properties of InAs∕GaAs quantum dots grown by migration enhanced epitaxy, with and without arsenic, during indium deposition. The uniformity and size of the quantum dots are enhanced in a sample without arsenic. As a result, narrower and longer wavelength photoluminescence is observed in this sample. Furthermore, the thickness of the wetting layers is reduced by ∼20% in the sample without arsenic, and this result agrees well with the speculation that metallic indium has a smaller driving force for corrugating the InAs wetting layers before they are transformed from two-dimensional to three-dimensional layers. Additionally, the photoluminescence linewidth of the sample without arsenic is insensitive to the cryostat temperature due to two major factors: the reduced thickness of the wetting layers and the enhanced uniformity. In the sample with arsenic, however, the photoluminescence linewidth shows typical anomalies.
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