The Photoluminescence of Flames

Abstract

Effect of light on the intensity of the flame spectra of Li, Na, Ca, and Sr.—The salted flame of an air-hydrogen blast lamp was illuminated with the full light from a tungsten lamp, a carbon arc, a mercury arc and an iron spark, and the intensity of the bands or lines emitted, as determined by a photometric balance method in connection with a spectrometer, was found to be increased in all cases. The iron spark was most effective, the increases being over 10 per cent for Ca and Sr. Not only the ultra-violet beyond.3μ is effective but also light above.43μ. Red or yellow light of the wave-length absorbed by the flame, however, had a quenching effect, reducing the intensity 2 or 3 per cent and decreasing the effect of the spark alone by half. No change in the distribution of intensity in the spectra seems to be produced, all bands being equally affected. That true luminescence is produced is shown by the fact that the intensity is the same in all directions.