Measurement of the diffusion coefficients of metal vapors in graphite furnaces

Atomic dissipation in a graphite furnace, heated at a rate of approximately 10 Kms(-1), has been investigated. At such heating rates, atomic dissipation is separated by time from the atomization process, and the decay portion of the absorbance signal reflects the removal function. The diffusion coefficients of Ag, Au, Bi, Cd, Ga, In, Mn, Pb, Sb,Sn, Tl and Zn were determined by routine analytical signals obtained on commercial atomic absorption instrumentation, without any modification to the standard technique. The dynamic measurement of the effective gas temperature was carried out by the use of the two-line method, with Pb 368.3/280.2 nm, and Sn 286.3/284.0 nm line pairs. The agreement of the experimental data with the diffusion coefficients, calculated by the Chapman-Enskog theory, was obtained for all of the elements investigated; confirming the diffusional nature of atom removal for these elements, and as well the weak interaction of the atomic vapor with the graphite surface. (C) 2000 Elsevier Science B.V. All rights reserved.