Laser-Enhanced Ionization Spectrometry

Laser-enhanced ionization (LEI) is one of a family of laser-induced ionization techniques which have been exploited for analytical spectrometry. In LEI, a pulsed dye laser is used to promote analyte atoms to a bound excited state from which they are collisionally ionized in a flame. The resulting current is detected with electrodes and is a measure of the concentration of the absorbing species. LEI may proceed by photoexcitation (via one or more transitions) and thermal ionization or a combination of thermal excitation, photoexcitation, and thermal ionization. LEI detection limits are competitive with — and in many cases superior to — those obtained with other techniques of atomic spectrometry. This chapter will provide an introduction to LEI spectrometry and its capabilities. Signal production and collection will be discussed along with the more practical aspects of LEI spectrometry. The applications of LEI spectrometry will be reviewed and the future of LEI spectrometry will be assessed.