Laser-induced purification

A.V. Sharikova and D. K. Killinger, Laser-induced fluorescence studied of water processed by a reverse osmosis purification unit, Proc. ofSPlE 5994, 59940B-1-59940B-5 (2005). 

The occurrence of ZWRs and of EPs in fhe confexf of laser-induced photodissociation can be exploited in various ways. We have shown how ZWRs can be beneficial in purification scenarios. We have also shown that EPs can be exploited in vibrational transfer scenarios. Such scenarios could ultimately be applied for vibrational cooling strategies by depleting all vibrational levels except the ground (v = 0) one. 

Laser chemistry can also be used for purifying certain chemicals. The production of ultrapure silicon for the semiconductor industry and for producing solar cells is of special interest. For optical fibres the purest possible Si02 is desirable. A suitable starting material is silane gas. Arsine (ASH3) and phosphine (PH3) are typical impurities. On radiation of the natural gas mixture with an ArF excimer laser (A=193nm) the impurities are quickly dissociated. The technique has a good production potential and the cost for purification could be quite reasonable. Since the cost of the laser photons will always be an important factor it is likely that laser-induced... 

Analytical procedures for foods are generally based on extraction with purified solvents following saponification with alcoholic potash. Purification of the extracts by chromatography on column or plates is followed by analysis of the purified extract using TLC, GLC or HPLC. Spectrophotometric or spectrofluorimetric methods may be used for quantitation of the hydrocarbons a collaborative study of a spectrophotometric method showed it to be applicable at the 2 fig/kg level. HPLC techniques using spectrofluorimetric detection have been described for which improved levels of detection are claimed. Benzo(a)pyrene produces substitution products with nucleic acids. Hydrocarbon deoxyribonucleoside adducts may be isolated from DNA by gel permeation chromatography, and the formation of hydrocarbon epoxides by mammalian enzyme reaction has also been demonstrated . The limit of detection of spectrophotometric and fluorimetric methods has been improved by three orders of magnitude by the use of laser-induced fluorescence procedures for the... 

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