Laser photoionization spectroscopy of atomic traces at part per trillion levels

Abstract

The method of laser photoionization spectrometry (LAPIS), a combination of laser stepwise resonant photoionization of atoms with thermal atomization of the sample in a vacuum, was used for measuring ultra-low concentrations of Ga in germanium and Rh in environmental samples. The calibration curves constructed for aqueous Ga and Rh standards and Rh copper standards were linear over six orders of magnitude in element concentration. The detection limits for aqueous solutions were 3 and 5 ppt for Ga and Rh, respectively, for 100 μl samples. The thermal atomization of Ga and Rh compounds in a vacuum was investigated. It was shown that under optimum conditions complete (100% efficient) atomization takes place and the matrix composition is practically irrelevant to the analytical results. The possibility of standardless analysis by LAPIS is discussed. © 1988.