title: Effect of liquid-sheet thickness on detection sensitivity for laser-induced breakdown spectroscopy of aqueous solution.
abstract: For aqueous-solution-based elemental analysis, we used a thin liquid sheet (μm-scale thickness) in laser-induced breakdown spectroscopy with nanosecond laser pulses. Laser-induced plasma is emitted by focusing a pulsed Nd:YAG laser (1064 nm) on a 5- to 80-μm-thick liquid sheet in air. To optimize the conditions for detecting elements, we studied how the signal-to-background ratio (SBR) for Hα Balmer and Na-neutral emission lines depends on the liquid-sheet thickness. The SBR of the Hα Balmer and Na-neutral lines was maximized for a sheet thickness of ~20 μm at the laser energy of 100 mJ. The hydrodynamics of liquid flow induced by the laser pulse was analyzed by laser flash shadowgraph imaging. Time-resolved observation of the hydrodynamics and plasma emission suggests that the dependence of the SBR on the liquid-sheet thickness is correlated with the volume of flowing liquid that interacts with the laser pulses.
authors.forename: Hironori
authors.initials: H
authors.lastname: Ohba
authors.forename: Morihisa
authors.initials: M
authors.lastname: Saeki
authors.forename: Ikuo
authors.initials: I
authors.lastname: Wakaida
authors.forename: Rie
authors.initials: R
authors.lastname: Tanabe
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Ito