Despite the large neutral atomic and ionic emission enhancements that have been noted in collinear and orthogonal dual-pulse laser-induced breakdown spectroscopy, the source or sources of these significant signal and signal-to-noise ratio improvements have yet to be explained. In the research reported herein, the combination of a femtosecond preablative air spark and a nanosecond ablative pulse yields eightfold and tenfold material removal improvement for brass and aluminum, respectively, but neutral atomic emission is enhanced by only a factor of 3–4. Additionally, temporal correlation between enhancement of material removal and of atomic emission is quite poor, suggesting that the atomic-emission enhancements noted in the femtosecond–nanosecond pulse configuration result in large part from some source other than simple improvement in material removal.
© 2004 Optical Society of America
Original Manuscript: February 20, 2004
Revised Manuscript: September 6, 2004
Manuscript Accepted: September 21, 2004
Published: December 10, 2004
Jon Scaffidi, William Pearman, J. Chance Carter, Bill W. Colston, and S. Michael Angel, "Temporal dependence of the enhancement of material removal in femtosecond–nanosecond dual-pulse laser-induced breakdown spectroscopy," Appl. Opt. 43, 6492-6499 (2004)