8. Chemical Analysis by Laser Ablation

Abstract

Publisher Summary The chapter discusses the use of laser ablation for chemical analysis. In forensics, health, environmental, nonproliferation, and many other disciplines, the chemical composition of a sample can be consequential. For the semiconductor industry, a trace amount of impurity may cost millions of dollars in lost processing. The billion-dollar effort to remediate contaminated environmental sites requires venerable chemical analysis. For nonproliferation, chemical analysis may foretell covert development of nuclear or chemical weapons. In health, chemical analysis can save lives. The chapter emphasizes on direct solid-phase analysis; when a pulsed laser beam is focused onto any solid sample, a portion of the material is instantaneously transformed into vapor phase constituents. Chemical analysis can be performed directly within the luminous laser-induced plasma at the sample surface, or by transporting the ablated mass to a secondary excitation source for analysis. The goal is to break (ablate) the sample into a fine vapor with a stoichiometric representation of the solid phase. Some of the technologies that have been investigated for direct solid-phase chemical analysis include the following: slurry nebulization; arc and spark sampling; electro-thermal vaporization; direct insertion into an analytical source using graphite cups; exploding films; and reduced pressure rf discharges.