Flame photometric determinations of diffusion coefficients. Part 1.—Experimental and theoretical considerations

Abstract

The use of the point source method for determining diffusion coefficients of gases is extended to metal atoms in flames. The flames investigated initially are H₂+O₂+N₂ ones burnt at atmospheric pressure and have minute quantities of a metal added to them from a point source. The intensity of the resonance emission of the metal is used as a measure of the concentration of metal at different points in a flame, thereby enabling determinations of diffusion coefficients to be made. The general theory of a mathematical model of the technique is examined and simplifications made. In particular, conditions are established where diffusion of additive can be ignored in the direction of motion of the flame gases. The complications of compound formation from the metal and also ionization of it are dealt with. The experiment is capable of measuring rates of ionization, as well as coefficients of diffusion for the metal.