Fluorescence and phosphorescence of diamond at different temperatures
The electronic line at λ 4156 present in the fluorescence spectrum of all diamonds sharpens and increases in peak intensity on cooling the diamond;per contra, it broadens and decreases in peak intensity on increasing the temperature of the diamond and finally at 350°C. is lost in the background. The integrated intensity of the line has been investigated and found to be unaltered to any marked degree between − 180° C. and +150° C.
The phosphorescence of diamond at various temperatures has also been dealt with. At low temperatures the after-glow is weak and greenish-yellow in colour, while at 400° C., the glow is extremely intense and blue. The effect of quenching by red or green light on this bright and blue glow has been reported in this paper.