LASER MICROPROBE AND RESONANCE IONIZATION MASS-SPECTROMETRY FOR THE ANALYSIS OF TRACE-ELEMENTS IN SOLIDS

A laser microprobe and resonance ionization mass spectrometer (LAM/RIMS) has been designed and constructed by combining a newly designed simple laser microprobe (LAM) with a continuous-wave (cw) resonance ionization mass spectrometer, for the direct analysis of trace elements in solids. The LAM/RIMS has achieved a simultaneous record of the complete mass spectrum of a solid sample, and a three orders of magnitude enhancement in the detection signal of the selected trace elements in the solid, with precise spatial information, and without the need of sample preparation. A n-type silicon wafer containing an impurity of sodium in parts per billion order has been easily detected by applying a single shot of an ablation laser pulse and a cw resonance ionization laser. The result has also shown that the sensitivity of the LAM/RIMS for the analysis of selected trace elements is better than the Auger electron spectroscopy and is comparable to neutron activation analysis.