Detection of hydrated electrons in water-jet immersed in low-pressure plasma by laser-induced desolvation

Abstract

We detected hydrated electrons in a micrometer-size water jet immersed in a low-pressure plasma by laser-induced desolvation. When we irradiated the 2nd, 3rd, and 4th harmonics of Nd:YAG laser pulses to the water jet, we detected the pulsed current which indicated the transport of electrons from the water jet to the plasma. We observed a proportional relationship between the amplitude of the pulsed current and the laser energy, which is consistent with the conversion from hydrated to free electrons by laser-induced desolvation. The amplitude of the pulsed current increased with the negative bias voltage between the plasma and the water jet. The most remarkable result was found in the relationship between the photon energy and the quantum yield of the electron transport. The experimental quantum yield was orders of magnitude higher than that predicted by a Monte Carlo simulation in a low photon energy region, suggesting the possibility that hydrated electrons we detected in the present experiment have much lower hydration energies than well-known hydrated electrons.