Laser optically dense samples

There has been renewed interest in the method, mainly due to the availability of improved Nd YAG laser systems. In addition, different types of detectors, such as microchannel plates coupled to photodiodes and CCDs, in combination with multi-channel analyzers make it possible for an analytical line and an internal standard line to be recorded simultaneously, by which the analytical precision can be considerably improved. By optimizing the ablation conditions and the spectral observation, detection limits obtained using the laser plume as a source for atomic emission spectrometry are in the 50-100 pg/g range and RSDs are in the region of 1% as shown by the determination of Si and Mg in low-alloyed steels [255, 259]. This necessitates the use of slightly reduced pressure, so that the atom vapor cloud is no longer optically very dense and the background emission intensities become lower. In the case of laser ablation of brass samples at normal pressure and direct... 

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