Abstract

Direct laser ionization (DLI) proceeds by resonant excitation of analyte followed by photoionization of the excited-state atoms. Photoionization is accomplished with the use of off-resonant radiation, which is usually obtained from the dye laser pumping source. DLI has been shown to enhance ionization yields, relative to laser-enhanced ionization (LEI), in low-temperature atom reservoirs where collisional ionization is inefficient. In the present study, DLI has been demonstrated in high-temperature, analytically useful flames, with similar results. DLI detection limits and spectral interferences, as well as the effects of photoionizing laser power on ionization yield, have been evaluated.

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)

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)

Experimental demonstration of a Raman scattering detector based on laser-enhanced ionization

B. W. Smith, P. B. Farnsworth, J. D. Winefordner, and N. Omenetto
Opt. Lett. 15(14) 823-825 (1990)

Use of laser-induced ionization to detect soot inception in premixed flames

Samuel L. Manzello, Eui Ju Lee, and George W. Mulholland
Appl. Opt. 44(24) 5105-5111 (2005)