Image intensifier studies of low intensity triboluminescence, electroluminescence and photoluminescence of solids

Chapman, Geoffrey N (1981). Image intensifier studies of low intensity triboluminescence, electroluminescence and photoluminescence of solids. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000fc8b

Abstract

A four-stage magnetically focused image intensifier tube (IIT) with an optical power gain of about 106 was used in both spatial and spectral investigations of solids.

The spectral studies involved the design and construction of a spectrograph to disperse light across the input photocathode of
the IIT. Spectra were then amplified by the IIT and displayed on the output phospher where they were photographically recorded. The system was intensity corrected and used to measure the triboluminescence (TL) spectra from small quantities (- 10 grams) of material. The TL spectra of minerals including amethyst, zircon, and various calcites and fluorites were recorded for the first time with high spectral resolution. Origins of these TL spectra were investigated, and many were correlated with appropriate term diagrams. The results are discussed following a detailed and critical review of the literature. Light emission from cutting a number of glasses and polymers on a diamond saw was also recorded and the (continuum like) spectra obtained were compared with black body radiation (at the temperature estimated to occur at a crack tip due to release of plastic deformation energy). Differences were noted in some cases between the TL which occurred at fracture and the light emission of the same samples when cut on the diamond saw. These differences are discussed with reference to the photoluminescence spectra of the samples. Thermoluminescence spectra were also recorded, again using an IIT spectrograph, and the results were compared with TL of similar specimens.

A spatial study of semiconductors was made by projecting the image of a small area (typically 50 um2) of the specimen, using a microscope, onto the input photocathode of the IIT. The high optical power gain of the system was utilized in a 'spatial investigation of semiconductor electroluminescence (EL) and photoluminescence (PL). The EL of GaP and Ga1-xAlxAs (x = 0.35 and 0.52) was recorded and the EL of the latter was compared with cathodoluminescence of the same specimen to highlight the complementary nature of the techniques. The homogeneity of the PL of a sample of amorphous silicon was studied at 77K in a specially constructed cryostat. The application of the method to other homogeneity measurements is discussed.

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