Fiber optic probe for determining heavy metals in solids based on laser-induced plasmas

Abstract

A fiber-optic probe suitable for remote elemental analysis using laser-induced breakdown spectroscopy (LIBS) has been developed and has been used to determine the concentration of lead in samples of dry paint. To develop a suitable fiber- optic sensor for remote measurements using LIBS a number of key issues must be addressed. The issue of coupling high-power laser pulses into optical fibers without fiber damage was first addressed by measuring damage threshold values, and by performing long-term durability tests for several different fiber types and sizes. This study led to the design of a highly flexible fiber-optic LIBS probe that can be used for a variety of sample substrates. To address the issue of reproducibility, we are investigating matrix affects and the dynamics of the laser ablation and laser-induced plasma processes by using a variety of spectroscopic techniques including time-resolved spectroscopic imaging. We have also modified the probe so that laser ablated material can be injected into a mass spectrometer.