Fluorescence of Atomic Germanium – Solution of Excitation Transfer

Abstract

Laser induced fluorescence was used for detection of free germanium atoms in a miniature diffusion flame atomizer. Two excitation schemes were tested, which were based on excitation wavelengths around 250 nm and 205 nm. The second scheme suffered from a fast collisionally induced excitation transfer to another radiative state, which could led to an erroneous overestimation of Ge concentration by an order of magnitude. The excitation transfer was quantified and the problem was solved by means of measurement of temporally resolved fluorescence spectra. The equations for evaluation of fluorescence measurements affected by an excitation transfer to radiative states are presented. The obtained Ge concentration profiles revealed a strongly inhomogeneous distribution of free Ge atoms and a low germane atomization efficiency in the flame.