Plasma dynamics of water breakdown at a water surface induced by femtosecond laser pulses

Abstract

Femtosecond laser pulse induced ultrafast plasma dynamics studies of water breakdown in the range up to 250ps are reported. We combine transient imaging techniques together with spectrally resolved reflection spectroscopy to monitor the early breakdown dynamics at the water surface with a laser intensity being 1.5 above threshold. We observe a 20ps delay before the plasma expands with an initial velocity of 5900m∕s. The transient electron density after formation of the plasma is 1.2×1021∕cm3. A recombination on a picosecond time scale with a rate of (1.6×10−9±0.3×10−9)cm3∕s is found.