Resonance-enhanced multiphoton ionization (REMPI) is investigated as a potential technique for real-time monitoring of selected volatile organochloride compounds (VOCs). In a proof-of-concept experiment, the progress of the reductive-degradation of tetrachloroethylene (PCE) to trichloroethylene (TCE) by zero-valent zinc was monitored by REMPI measurements performed in the headspace above the PCE solution. Two-photon resonant REMPI spectra of TCE and PCE were recorded over the wavelength range 305–320 nm. The concentrations of PCE and TCE in the headspace were monitored by measurement of the ionization signal with 315.64- and 310.48-nm excitation for PCE and TCE, respectively. Calibration curves yielded a linear range of more than 2 orders of magnitude for both compounds. The REMPI headspace results agreed well with the solution-phase results from gas chromatography analysis, which was used for independent verification of the progress of the reaction.
© 2004 Optical Society of America
(020.4180) Atomic and molecular physics : Multiphoton processes
(260.5740) Physical optics : Resonance
(300.6350) Spectroscopy : Spectroscopy, ionization
(300.6360) Spectroscopy : Spectroscopy, laser
Kui Chen, Jack E. Pender, John L. Ferry, and S. Michael Angel, "Resonance-Enhanced Multiphoton Ionization for Real-Time Monitoring of Trichloroethylene Formed by Degradation of Tetrachloroethylene Using Zero-Valent Zinc," Appl. Opt. 43, 6207-6212 (2004)