ANALYTICAL CHARACTERIZATION OF LASER-EXCITED ATOMIC FLUORESCENCE OF BISMUTH

The possibilities of direct determination of Bi traces by laser excite d atomic fluorescence spectrometry were investigated. Practically all one-color excitation-detection schemes were examined. For the resonanc e fluorescence at 306.8 nm, the main source of background was a molecu lar fluorescence of residual water vapors. The background characterist ic OH rotational lines of 0-0 band of (2) Sigma - (II)-I-2 transition were registered in the excitation spectra. From the relative intensiti es of the rotational components, the gas temperature of the analytical volume above the open graphite cup of the atomizer was estimated as 6 80 +/- 120 degrees C. A detection limit (LOD) of about 1 pg/ml was ach ieved for the resonance scheme. For the excitation wavelength shorter than 230 nm, broadband fluorescence of unidentified species in the 300 -400 nm spectral range was the main source of background. The best LOD of 0.05 pg/ml was realized for the 223.1/299.3 nm excitation-detectio n scheme. This LOD is the best one for the one-color LEAFS technique. Possible ways of further increasing the LEAFS sensitivity of Bi traces detection are briefly discussed.