Selenium hydride atomization, fate of free atoms and spectroscopic temperature in miniature diffusion flame atomizer studied by atomic absorption spectrometry

The mechanism of hydride atomization and the fate of free atoms was investi gated in the miniature diffusion flame. Selenium hydride was used as a mode l for the other hydrides. Mercury vapor was employed as an analyte to study physical processes, such as macroscopic movements and free atom diffusion, controlling the distribution of free analyte atoms in the observation volu me, separately from chemical reactions of the free atoms. Free atoms were d etected by atomic absorption spectrometry. Spectroscopic temperature measur ements based on atomic absorption at 196.1 and 204.0 nm Se lines were used to determine the temperature distribution. The spatial temperature distribu tion was highly inhomogeneous ranging from 150 degrees C to 1300 degrees C. The whole flame volume is actually a cloud of hydrogen radicals maintainin g analyte in the free atom state since hydrogen radicals formed in outer zo ne of the flame diffuse to its cooler inner parts. (C) 1998 Elsevier Scienc e B.V. All rights reserved.