Detailed results of the overall thermal degradation of poly(butylene terephthalate) are reported. Laser microprobe analysis and dynamic mass spectrometric techniques were used to identify the primary volatile degradation products and initial pyrolysis reactions that control polymer degradation. A complex multistage decomposition mechanism was observed which involves two major reaction pathways. Initial degradation occurs by an ionic decomposition process that results in the evolution of tetrahydrofuran. This is followed by concerted ester pyrolysis reactions that involve an intermediate cyclic transition state and yield 1,3‐butadiene. Simultaneous decarboxylation reactions occur in both decomposition regimes. Finally, the latter stages of polymer decomposition were characterized by evolution of CO and complex aromatic species such as toluene, benzoic acid, and terephthalic acid. Activation energies of formation for the main pyrolysis products were determined from the dynamic measurements of the major ion species and indicate values of E = 27.9 kcal/mole for the production of tetrahydrofuran and E = 49.7 kcal/mole for the production of butadiene.

A theoretical model that predicts the spatial resolution for grating formation on n-type semiconductors by photoelectrochemical etching has been developed. The ratio of the amplitude of the grating to the average depth etched by a sinusoidal spatial variation of light intensity was determined from a model that takes into account the drift and two-dimensional diffusion of the photogenerated holes and their rate of reaction at the surface. Experimental measurements of the growth of gratings agree with the predictions of the theory for the dependence on the period of the grating, the carrier concentration of the semiconductor, and the wavelength of the light. Fitting the experimental data to the theory provides a novel method for determining the reaction velocities of the decomposition reaction in different electrolytes. The theory predicts that large improvements in the resolution would be possible if electrolytes giving higher reaction velocities could be found.

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Heterojunctions of n-type InAs0.95Sb0.05 grown by metalorganic chemical vapor deposition on n-type GaSb substrates were studied by capacitance-voltage and current-voltage measurements. The n-n heterojunctions are strongly rectifying and behave like metal-(n) GaSb Schottky diodes with a barrier height of 0.80±0.02 eV. These measurements establish that the band lineup in this system is of the broken gap variety. We measure the valence-band offset, Ev(GaSb)−Ev(InAs0.95Sb0.05), to be 0.67±0.04 eV.