Laser-Induced-Fluorescence Detection of Sodium Atomized by a Microwave-Induced Plasma with Tungsten Filament Vaporization

The laser-induced-fluorescence (LIF) technique is applied to the detection of Na atoms In pure water for a concentration range down to pg/cm³. Na compounds are dissociated by a microwave-Induced plasma of He with a tungsten filament vaporization system. Calibrating the absolute density at the observing region, the efficiency of this atomizer Is estimated. It Is shown that the atomizer can generate high atomic densities by filament heating. For example, the number density reaches 10⁷ atoms/cm³ for a 10-μL sample of 1 pg/cm³.