title: Observations in collinear femtosecond-nanosecond dual-pulse laser-induced breakdown spectroscopy.
abstract: In the work reported herein, we have combined a short-lived femtosecond laser-induced plasma (LIP) and a longer-lived nanosecond LIP in a collinear pulse configuration to examine the source(s) of atomic emission and signal-to-noise enhancement in dual-pulse laser-induced breakdown spectroscopy (LIBS). Initial studies indicate that the primary source of dual-pulse LIBS enhancement in the collinear configuration may in large part be a matter of pulse focus; focusing on the sample surface, for example, yields atomic emission enhancements whose lifetime correlates reasonably well with the femtosecond LIP emissive lifetime, suggesting that plasma-plasma coupling may play an important role at that pulse focus. At a second "optimal" focal position above the sample surface, alternatively, atomic emission and signal-to-noise enhancements correlate quite well with the nitrogen and oxygen atomic emission reductions previously seen following use of a femtosecond air spark and a nanosecond ablative pulse in the orthogonal dual-pulse configuration, suggesting that pressure or number density reductions due to femtosecond LIP formation in air may be significant at that pulse focus.
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: J
authors.initials: J
authors.lastname: Scaffidi
authors.forename: W
authors.initials: W
authors.lastname: Pearman
authors.forename: J C
authors.initials: JC
authors.lastname: Carter
authors.forename: S M
authors.initials: SM
authors.lastname: Angel
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000032:analysis*; D006358:Hot Temperature; D007834:Lasers; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D013057:Spectrum Analysis / Q000379:methods*; D013997:Time Factors
chemical_list: D005740:Gases