Laser-induced ionization water

SINGLE-PHOTON INFRARED PHOTOCHEMISTRY WAVELENGTH AND TEMPERATURE DEPENDENCE OF THE QUANTUM YIELD FOR THE LASER INDUCED IONIZATION OF WATER... 

Absorption of UV or visible light from a flash lamp or a laser is used to produce the solvated electron, too. Two photolytic processes may occur (1) the photon energy is sufficient to ionize a solute and produce the electron, for instance, photo-detachment from an anion (Cl , Fe(CN)g , Na ...) (2) the laser intensity is high enough to induce ionization of the solvent via multiphoton absorption (e.g. HjO -I- hv 112 + e ). For water, at least 8 eV is needed to ionize the solvent. 

Since in densely populated industrial areas air and water pollution has become a serious problem, the study of pollutants and their reactions with natural components of our environment is urgently needed [15.75]. Various techniques of laser spectroscopy have been successfully employed in atmospheric and environmental research direct absorption measurements, laser-induced fluorescence techniques, photoacoustic detection, spontaneous Raman scattering and CARS (Chap. 8), resonant two-photon ionization, and many more of the sensitive detection techniques discussed in Chap. 6 can be applied to various environmental problems. This section illustrates the potential of laser spectroscopy in this field by some examples. 

We shall initially summarize the evidence proving that absorption of one laser photon by water induced ionization to hydrogen and hydroxyl ions. 

Within the PLP-SEC experiments on non-ionized MAA in the presence of poly(MAA), the determination of points of inflection, via the maxima in the associated first-derivative curves of the MWD, is complicated by the pre-mixed polymer which obviously can not be removed prior to SEC analysis. Figures 2 and 3 depict MWDs (A) and the associated first-derivative curves (B) of polymer samples obtained by PLP-induced polymerizations of 15 wt.-% MAA dissolved in water containing 5 wt.% of pre-mixed polymer and of 10 wt.-% MAA dissolved in water containing 10 wt.-% of pre-mixed polymer, respectively. The full lines (a) represent the polymer sample after pulsed laser polymerization, whereas the dashed... 

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