A TIME-RESOLVED IMAGING STUDY OF CR(I) EMISSIONS FROM A LASER-PLASMA FORMED ON A SAMPLE AT NONNORMAL INCIDENCE

The effect of sample orientation on atomic emission in laser-induced b reakdown spectroscopy (LIBS) was studied using time-resolved imaging a nd spectroscopy. The purpose of this work was to determine the effect of sampling geometry on the analytical performance of the LIBS measure ment. The results obtained indicate that atoms are ejected perpendicul ar to the sample surface independent of the angle-of-incidence of the laser pulse. This result is consistent with previous work by others, I n addition, it was found that the observed LIBS atomic emission intens ities were maximum for normal laser pulse incidence, reached a minimum at 50 degrees angle-of-incidence, and then increased as the sample wa s rotated to higher angles-of-incidence.