Atmospheric Dust and Fluorescence

Abstract

MANY chemicals and minerals show a bluish fluorescence that can be destroyed by strong heating but is regenerated, after exposure to the air, by lesser heating¹; I have called this reversibility of fluorescence by annealing. Stimulated by the well-known experiments of Ewles, I ascribed this to the action of adsorbed water, but recent experiments have shown that this interpretation is not sufficient and that the effect is due to dust most likely of organic origin deposited from the atmosphere; subsequent heating-causes an interaction between this dust and the inorganic powder (SiO₂,Al₂O₃) used in these experiments, and this gives rise to stronger fluorescence.