ESTIMATION OF FREE-ATOM FRACTION AND DISSOCIATION ENERGIES OF COMPOUNDS IN FLAMES BY AN ATOMIC ABSORPTION METHOD

By means of a relative atomic absorption technique, the degrees of atomization, β, of a number of elements in a shielded premixed, laminar acetylene-air flame (2410°K) were measured. In this method the absorption of each element is compared with the absorption of copper. The results are not a function of the wavelength dependence of the photodetector, and it is not necessary to accurately measure the spray efficiency of the nebulizer, the solution transport rate, losses of solution in the interconnecting tubing and the spectral bandwidth of the monochromator. Also relative oscillator strengths are more accurately known than absolute values. The measured β- values for Ca, Ba and Sr agree quite well with calculated β-values assuming thermal equilibrium. The measured β-values for Mg, Cr, Fe and Mn were used to estimate the dissociation energies of the monoxides to within ±0.1 eV. Other uses of the measured β-values, such as estimation of oscillator strengths and the concentration of atomic oxygen in the flame gases are discussed. © 1969.