Balance of O2 and H2 content under laser-induced breakdown of aqueous colloidal solutions

TL;DR

This study investigates the formation and balance of hydrogen and oxygen gases produced by laser-induced breakdown in water colloids, revealing how laser fluence influences gas ratios and discussing potential dissociation mechanisms.

Contribution

It provides experimental insights into gas formation dynamics under laser exposure and explores how laser parameters affect H2 and O2 balance in colloidal solutions.

Findings

H2 and O2 partial pressures increase and saturate after about 1 hour of laser exposure.

Higher laser fluences shift the gas balance towards H2.

Possible dissociation mechanisms include plasma breakdown and direct water molecule dissociation.

Abstract

Formation of molecular H2 and O2 is experimentally studied under laser exposure of water colloidal solution to radiation of a Nd:YAG laser at pulse duration of 10 ns and laser fluence in the liquid of order of 100 J/cm2. It is found the partial pressure of both H2 and O2 first increases with laser exposure time and saturates at exposures of order of 1 hour. The balance between O2 and H2 content depends on the laser energy fluence in the solution and is shifted towards H2 at high fluences. Possible mechanisms of formation of the dissociation products are discussed, from direct dissociation of H2O molecules by electrons of plasma breakdown to emission of laser-induced plasma in liquid.