Laser-induced single-resonance and double-resonance atomic fluorescence spectrometry in a graphite tube atomiser

Abstract

One or two tunable dye lasers were axially directed through a commercial graphite furnace tube atomiser to excite the atomic fluorescence of the elements Tl, Pb and Cd. Scattering problems are overcome by exploiting single-step excited direct line fluorescence for Tl and Pb and two-step excited thermally assisted fluorescence for Cd. The optical layout did not require any modification of the graphite tube assembly as the fluorescence emission was collected with a plane mirror placed at one aperture of the tube at 45° with respect to the excitation axis. The mirror was pierced at the centre to allow the passage of the laser beam(s). The absolute detection limits for Tl, Pb and Cd in acidified solutions were found to be 2, 5 and 18 fg, respectively.