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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
421

Electrical and optical properties of novel phthalocyanine compounds for sensor devices

Exley, James Richard January 1995 (has links)
UV/visible spectrophotometry measurements, together with measurement of the temperature dependence of ac parameters G (conductance), C (capacitance) and tan (dielectric loss) for 20Hz<f<1MHz, and dc conduction, for 77K<T<300K, are performed for a number of vacuum-sublimed phthalocyanine compounds. Steady state electrical measurements and optical absorption experiments were performed on samples of sublimed heavy fraction rare-earth element, fluorochromium and lutetium bisphthalocyanine films. From the Arrhenius plot of ln(T) (where (T) is the conductivity at temperature T) it is found that two conduction regimes exist. The activation energy in the order 0.2eV at high temperatures (T > 162K) relates to the distance of singlet states below the conduction band. The low temperature activation energy indicates hopping conduction between localised states close to the Fermi level. Visible optical absorption and transmission spectra are obtained for 50nm thick sublimed films of heavy fraction rare-earth [HF(pc)(pc*)], gadolinium [Gd(pc)(pc*)] and thulium [Tm(pc)(pc*)] bisphthalocyanine compounds when they have undergone the postdeposition treatments of voltage-cycling to blue, voltage cycling to red and annealing at 393K for one hour; also for untreated fluorochromium phthalocyanine. The different post-deposition treatments produce different effects on the absorption spectra; in the case of annealing, this is attributed to the phase changes occurring in the films. The changes due to the voltage cycling are believed to be a result of oxidation processes taking place in the materials. Absorption data are also analysed in order to obtain information regarding the dispersion of refractive index and dielectric constants within optical frequency range. Absorption data are analysed in terms of a well known power law, and a value of 2.3eV is found for the optical gap E0. in HF (pc)(pc*)
422

Mathematical problems in liquid crystal theory and elastic plate theory

Kidd, Julie Elizabeth January 2000 (has links)
No description available.
423

An experimental study of chemical diffusion in thin film binary alloys exhibiting intermediate phase formation

Fouracre, R. A. January 1980 (has links)
No description available.
424

(F←2'+)←H centre in oxygen-doped NaCl crystals

Williamson, Brian January 1989 (has links)
No description available.
425

Determination of organic crystal structures by X ray powder diffraction

McBride, Lorraine January 2000 (has links)
No description available.
426

Benard instabilities in liquid crystals

Fraser, C. January 1983 (has links)
No description available.
427

Some topics in continuum theory of liquid crystals

Anderson, Claire January 2000 (has links)
No description available.
428

A study of certain factors which influence solute permeability of polymer films

Okor, R. S. January 1980 (has links)
No description available.
429

Order parameters in liquid crystals

Davidson, A. N. January 1989 (has links)
No description available.
430

Optical fibre waveguides prepared by chemical vapour phase reaction and deposition techniques

Irven, J. January 1984 (has links)
No description available.

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