Insights in the laser induced breakdown spectroscopy signal generation underwater using dual pulse excitation - Part II: Plasma emission intensity as a function of interpulse delay

► DP-LIBS signal dependence in liquids on interpulse delay is fully explained. ► Formation and detection of the plasma depend on optical properties of the gas bubble. ► In the expanded bubble the signal recovers by Snell's reflections at the interface. ► Lifetime of the secondary plasma reduces with the bubble expansion. ► Transitions of pressure waves through the focal volume enhance the DP-LIBS signal.