QUANTITATIVE SIMULTANEOUS ELEMENTAL DETERMINATIONS IN ALLOYS USING LASER-INDUCED BREAKDOWN SPECTROSCOPY (LIBS) IN AN ULTRA-HIGH-VACUUM

Laser-induced breakdown spectroscopy (LIPS) in an ultra-high vacuum is used in simultaneous quantitative elemental analysis of NIST transiti on metal alloy samples. A plasma is formed by focusing a Nd:YAG laser onto the sample's surface inside a vacuum chamber. UV-visible emission from excited species is monitored with the use of an optical multicha nnel analyzer (OMA). Linear calibration curves are shown for the eleme nts (percent composition) Al (0.2-1.2%), Cu (0.021-0.49%), Fe (4.5-51. 0%), Ni (30.8-80.3%), and Zn (6-12.8%) with the use of nonresonant lin es. Detection limits (signal-to-noise = 3) vary with sample compositio n complexity from 0.0001% for Ni in a simple copper alloy (SRM 1111)to 0.16% for Al in a complex granular sample (SRM 349a). Absolute detect ion limits are estimated to be in the 20-200 mu g/g range for the elem ents of interest. Simultaneous mass spectra were taken by sweeping the magnetic field of a mass spectrometer. Preliminary results showed the magnet could not be swept fast enough for multielement analysis. The use of a position-sensitive ion detection system is proposed.