Abstract

Stepwise excitation laser-enhanced ionization spectroscopy utilizes two independently tunable dye lasers to populate high-lying excited states of atoms in flames. Two atomic resonances are required, with the upper level of the first-step transition coinciding with the lower level of the second-step transition. Efficient population of a high-lying atomic level is achieved, from which a high rate of collisional ionization can take place. The double-resonance aspect of such excitation adds an extra dimension of spectroscopic selectivity to the measurement. A computer-controlled dual-wavelength LEI spectrometer, including a Fizeau wave-meter for wavelength verification, is used to record three-dimensional spectra—ionization signal as a function of both first- and second-step wavelengths. Examples illustrate the accuracy advantage accorded by the three-dimensional survey.

Laser-enhanced ionization detection of trace copper in high salt matrices

George J. Havrilla and Christopher C. Carter
Appl. Opt. 26(17) 3510-3515 (1987)

Detection of traces in semiconductor materials by two-color laser-enhanced ionization spectroscopy in flames

Ove Axner, Mats Lejon, Ingemar Magnusson, Halina Rubinsztein-Dunlop, and Sten Sjöström
Appl. Opt. 26(17) 3521-3525 (1987)

Laser spectroscopy of U i using stepwise excitation and fluorescence detection

E. Miron, R. David, G. Erez, S. Lavi, and L. A. Levin
J. Opt. Soc. Am. 69(2) 256-264 (1979)

Laser-enhanced flame ionization detector

Terrill A. Cool and John E. M. Goldsmith
Appl. Opt. 26(17) 3542-3551 (1987)

Detection of trace amounts of Cr by two laser-based spectroscopic techniques: laser-enhanced ionization in flames and laser-induced fluorescence in graphite furnace

Ove Axner and Halina Rubinsztein-Dunlop
Appl. Opt. 32(6) 867-884 (1993)