Laser-induced fluorescence spectrometer based on solid state tunable color-center laser for heavy metal analysis

摘要

All solid state (SS) laser induced fluorescence (LIF) spectrometer based on tunable LiF:F$-2$/$+$MIN$/ color center (C.C.) MALSAN laser with second and fourth harmonic generation was optimized for trace metallic concentration measurements in water solutions. Two types of heavy metals atoms Sn and Pb were analyzed using inexpensive low temperature types of the propane/butane-air flames. The maximum sensitivity of 10 and 50 ppb with good linearity of fluorescence intensity concentration dependence was obtained for Sn and Pb atoms, respectively, using a monochromator for the fluorescence wavelength selection. When the monochromator was replaced by a set of color optical filters the sensitivity of 0.3 ppb for Pb atoms was obtained. Hence, the sensitivity was increased more than 150 times for more cheap and simple registration set-up. An attempt was made to use more compact super- broadband LiF:F$-2$/$+$MIN$/ C.C. laser to replace the MALSAN laser in LIF spectrometer. Up to now the sensitivity of 1 ppm for Pb with the monochromator based fluorescence registration system was obtained in the latter case.