Flame Atomic Absorption Spectroscopy Using a Single-Mode Laser Diode as the Line Source

Abstract

The laser diode recently has been applied to atomic spectroscopy in laser-enhanced ionization spectroscopy, laser-excited atomic fluorescence spectroscopy, resonance ionization mass spectrometry, and atomic absorption spectroscopy (AAS). Its attractive features include its having a low cost and being compact and tunable. Its major limitation is that commercial laser diodes are available only for fundamental wavelengths over the range of 670 to 1550 nm, and the tunability covers only several nanometers. In the AA investigation, a single-mode laser diode was used as the line source. Background correction was achieved by detuning the radiation to an off-resonance position; and the linear dynamic range could be extended by using the shoulder portion of the resonance line. Simultaneous multielement detection and internal standardization could be accomplished by the simultaneous use of several laser diodes. The atom reservoir employed was a graphite furnace and the detection spectrometer was a Fourier analyzer. We report here our observation of a single-mode laser diode used as the line source in flame AAS, with a simple, low-resolution monochromator and photomultiplier tube for detection. A multimode laser diode flame AAS has been reported in a separate paper.