LASER INDUCED FLUORESCENCE AND IONIZATION SPECTROSCOPY AS AN ANALYTICAL TOOL
Two pulsed tunable dye lasers, simultaneously pumped by an excimer laser are made temporally and spatially coincident and then directed into a flame or in an inductively coupled argon plasma, where both fluorescence and ionization techniques are studied. It is shown that in an air - acetylene flame, the stepwise excitation with two transitions allows to efficiently pump a level near the ionization potential of the element sought. This results in a collisionally assisted ionization process which proceeds very rapidly during the laser excitation pulse. The elements investigated (Ag, Na, Li, Pb, Sr, In and Tl) gave aqueous detection limits of the order of nanograms/liter and below. Because of this effective ionization, atomic fluorescence from highly excited states does not result in similar sensitivities. However, it is shown that one can take advantage of the ionic fluorescence generated in the inductively coupled plasma, since the level reached by the stepwise process is well below the second ionization potential of the ion. In this case, as shown for Ca, Sr, Ba and Mg, in addition to the sensitivity, the technique offers unprecedented spectral selectivity and freedom from scattering problems.
Bibliographic Reference: 2ND HUNGARO-ITALIAN SYMPOSIUM ON SPECTROCHEMISTRY, BUDAPEST (HUNGARY), JUNE 9-16, 1985 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 32059 ORA
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Record Number: 1989123096100 / Last updated on: 1987-01-01
Available languages: en