Abstract
A microscopic spectrophotometer that aims at measuring the photo-luminescence and visible ray absorption spectra has heen constructed. The energy levels relating to the photo-luminescence and the color of zircon of zircon were examined by using the spectrophotometer.
The photo-luminescence spectrum of zircon is composed of two types of spectrum : type I is line spectra originated from RE3+(rare earth elements such as Tm, Dy, Tb, Er, Eu, Sm, in which Dy is most dominated), type II is formed by broad bands originated from various levels, which may be created from radiation centers due to the decay of radioactive elements (U, Th) contained in zircon. Type II spectrum is diminished by the heat treatment and becomes extinct completely at above 650° C. However, type II luminescence is restored to the initial level for about I week in the V-excitation. The UV-excitation spectrum of this type is not restored so rapidly like as in the case of V-excitation. It is interesting that the spectral shape of UV-excitation (intensity of the luminescence) is gradually changed with geologicad age of zircon.
