An improved method for laser processing that prevents material redeposition during laser ablation but allows material to be removed at a high rate. In a preferred embodiment, laser ablation is performed in a chamber filled with high pressure precursor (etchant) gas so that sample particles ejected during laser ablation will react with the precursor gas in the gas atmosphere of the sample chamber. When the ejected particles collide with precursor gas particles, the precursor is dissociated, forming a reactive component that binds the ablated material. In turn, the reaction between the reactive dissociation by-product and the ablated material forms a new, volatile compound that can be pumped away in a gaseous state rather than redepositing onto the sample.