F-Centres in Metaphosphate Glass
A NUMBER of investigators1 have shown that glass on exposure to radioactive and X-radiation becomes coloured. Sheline, Sharp and Arner2 suggested that this may be due to F-centres similar to those produced in alkali halides when bombarded by X-rays and cathode rays. Yokota3 found that F-centres could be created in fused silica and α-quartz by X-irradiation. He further showed that alkali silicate and borate glasses become coloured on X-irradiation due to formation of F-centres4. Przibram5 showed that F-centres could also be created in borate glass by β- and γ-irradiation from radium.
Colour Centres in Metaphosphate Glass
IN a recent communication1, Basu states that we have attributed the coloration of metaphosphate glasses, induced by X-rays, to the activating influence of the metal (aluminium, barium, silver, etc.) in the glass, and that his results with sodium metaphosphate glasses show that ‘F-centres’ can be produced without these activators. In the references to our work cited by Basu2,3, the point is made that radiophotoluminescent centres having certain specific properties are connected with the presence of silver in potassium–barium–aluminium metaphosphate glass. It is clearly shown, we believe, in the publications from this Laboratory3–5 that a visible coloration is produced upon X-irradiation of the above silver-free base glass, two broad bands appearing with peaks at about 420 mµ and 530 mµ. These colour centres were not attributed to any ‘activating’ influence of the aluminium, barium or other metallic constituents of the glass.
Investigating the Optical properties of cd1-xznxs thin films deposited by the Dip Technique
A Thesis submitted to the Department of Physics, Kwame Nkrumah University of Science and Technology, in partial fulfillment of the requirement for the degree of 
Master of Science (Solid State Physics)