This thesis is primarily concerned with far infrared effects in semiconductor heterostructures. These properties have been studied as a function of magnetic fields at low temperature using various optical detection techniques. Cyclotron resonance has been studied in CdTe quantum wells. The results are compared with calculations using the memory function approach, which demonstrate that there is a large reduction in the resonant coupling due to level occupancy effects. Semimetallic GaSb/InAs superlattices have been studied by cyclotron resonance experiments. In samples with low InAs/GaSb ratios (~1), a pinning between the heavy hole subbands is predicted by theory which results in a suppression of heavy hole resonance at high magnetic fields. Photoluminescence measurements on a series of ultra-high mobility GaAs/AlGaAs heterojunctions have been performed. It has been found that the modulation caused by far infrared beam is entirely dependent on the filling factors, which is understood as the Landau level coupling effects between the subbands of 2DES. A GaAs/AlGaAs coupled quantum well photodiode has been studied by photoluminescence and photocurrent under the influence of far infrared beam. An enhancement of the photocurrent in the device is observed when the infrared photons are resonant with the intersubband transition between the anti-crossing electronic subbands of the coupled quantum wells, which makes the structure a potential tuneable far infrared detector. Most of the experimental works have been modelled with a k.p theory using momentum matrix approach. The self-consistency incorporated in this model proves to be useful while dealing with semimetallic or nonintrinsic systems. These calculations offer invaluable clues to the semiconductor heterostructures investigated.

An extensive literature survey has revealed that the majority of previous work in infrared image processing has ignored the processes leading to the formation of infrared images. Processing has normally either been restricted to simple lowlevel image enhancement convolutions or has consisted of algorithms copied from computer vision without regard for the inherent differences between infrared and visible images. In this thesis, we address the problem of infrared image formation and derive an irradiance equation for simple infrared scenes. We consider the complications caused by mutual illumination of one or more bodies and indicate how the infrared irradiance equation can also be specified for more complex scenes. The infrared irradiance equation we derive is solved in closed form for some simple geometries for both Lambertian and non-Lambertian surfaces. An infrared imager has been built and is described. Images taken with the imager of a variety of scene geometries show that the experimental results compare favourably with the theoretically derived equations, indicating the validity of the theoretical analysis. We describe how a knowledge of the formation of infrared images can be used to predict the image irradiance pattern of a particular object. We also show how, with a knowledge of the radiance properties and surface geometry of the object, it is possible to detect instances of that object in a scene. Examples are given of successful object detection based on an understanding of the image irradiance. We present a brief history of infrared imagers and a description of the principles on which modern infrared imagers are based. In addition to the survey of the literature published on infrared image processing, a brief summary of some techniques from the computer vision literature and their suitability to infrared image processing is given. A selection of vision techniques are applied to both infrared and visible images to verify conclusions reached in the thesis.

No description available.

Half of the sun’s power lies in the infrared. As a result, the optimal bandgaps for solar cells in both the single-junction and even the tandem architectures lie beyond 850 nm. However, progress in low-cost, large-area, physically-flexible solar cells has instead been made in organic and polymer materials possessing absorption onsets in the visible. Recent advances have been achieved in solution-cast infrared photovoltaics through the use of colloidal quantum dots. Here we report stable solution-processed photovoltaic devices having 3.6% power conversion efficiency in the infrared. The use of a strongly-bound bidentate linker, benzenedithiol, ensures device stability over weeks. We investigate in detail the physical mechanisms underlying the operation of this class of device. We find that diffusion of electrons and holes over hundreds of nanometers through our PbSe colloidal quantum dot solid is chiefly responsible for the high external quantum efficiencies obtained in this new class of devices.

No description available.

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1968. / Bibliography: leaves [83]-85. / viii, 85 l graphs, tables

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1972. / Bibliography: leaves [195]-199. / xiii, 199 l illus., tables

Gas phase anion clusters, consisting of solvent molecules hydrogen bonded to halide anions, are characterised by vibrational predissociation spectroscopy using a combination of mass spectrometry and laser spectroscopy. Monitoring changes in the vibrational properties of neutral solvent molecules when they are attached to a halide anion allows one to infer cluster structures. In some cases, the spectra contain rotationally resolved features, so that quantitative structural parameters can be obtained. (For complete abstract open document)

Thesis (M.S. - Agricultural Engineering)--University of Arizona, 1986. / Includes bibliographical references (leaves 96-99).

Thesis (M.S. - Soil and Water Science)--University of Arizona, 1986. / Includes bibliographical references (leaves 65-66).