Laser-excited atomic fluorescence spectroscopy LEAFS

Laser-excited atomic-fluorescence spectroscopy LEAFS... 

An example of the use of lasers in optimizing analyte detection is provided by the technique of laser excited atomic fluorescence spectroscopy (leafs). The detection of subfemtogram amounts of cadmium, thaUium, and lead has been reported (40). In this experiment, the sample of interest is first volatilized in a plasma (see Plasma technology) and then tuned photons from one or two dye lasers excite the analyte. When these atoms or ions relax, the resulting fluorescence signal is shunted into a photomultipHer for detection. Attomole detection levels are achievable using this technique. Continued advances in complex, multilaser spectroscopic determinations are expected to result in even lower levels of detection. 

Several techniques have been developed that use an electrothermal atomizer as an atom cell. Laser-induced fluorescence (LIF) has been discussed previously, but other techniques such as laser-excited atomic fluorescence spectroscopy (LEAFS) also exist, although not used routinely. 

LEAFS laser-excited atomic fluorescence spectroscopy... 

Electron diffraction spectroscopy ETA LEAFS Electrothermal atomisation laser-excited atomic fluorescence... 

In laser vaporisation experiments, generating a plume , the laser s frequency may be synchronised with the resonance line of the element (analyte) to be analysed. The basic principles are (i) absorption of the radiation by the analyte (LAAS laser atomic absorption spectrometry) (ii) fluorescence (LIE, laser-induced fluorescence LEAFS) or (Hi) production of ionisation products (ions and electrons). LIF is an analytical method of high precision that is suitable for the measurement of diatomic species in the plume. Excitation spectroscopy or laser-excited fluorescence is not concerned with the spectral composition of the fluorescence but with how the overall intensity of emission varies with the wavelength of excitation. 

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