We explore the use of a combination of double-pulse and single-pulse laser-induced breakdown spectros copy (LIBS) methodologies as a means of differentiating between solid-phase and gaseous-phase analytes (namely, carbon) in an aerosol stream. A range of spectral data was recorded for double-pulse and single-pulse configurations, including both ns and fs prepulse widths, while varying the gas-phase mass percentage of the carbon from about 10% to 90% for various fixed carbon concentrations. The carbon emission response, as measured by the peak-to-continuum ratio, was greater for the double-pulse configuration as compared with the single-pulse response and was also enhanced as the percentage of solid-phase carbon was increased. Using a combination of the double-pulse and single-pulse emission signals, a monotonically increasing response function was found to correlate with the percentage of gas-phase analyte. However, individual data points at the measured gas-phase percentages reveal considerable scatter from the predicted trend. Furthermore, the double-pulse to single-pulse ratio was only pronounced with the ns–ns configuration as compared with the fs–ns scheme. Overall, the LIBS methodology has been demonstrated as a potential means to discriminate between gas-phase and particulate-phase fractions of the same elemental species in an aerosol, although future optimization of the temporal parameters should be explored to improve the precision and accuracy of this approach.
© 2010 Optical Society of America
Original Manuscript: October 7, 2009
Revised Manuscript: February 16, 2010
Manuscript Accepted: February 17, 2010
Published: March 9, 2010
Michael E. Asgill, Michael S. Brown, Kyle Frische, William M. Roquemore, and David W. Hahn, "Double-pulse and single-pulse laser-induced breakdown spectroscopy for distinguishing between gaseous and particulate phase analytes," Appl. Opt. 49, C110-C119 (2010)