Ultraviolet laser ablation and decomposition of organic materials

Abstract

Pulsed, ultraviolet radiation from an excimer laser with wavelengths of 193nm or 248nm, a pulse width of about 20ns, and fluences above a threshold value causes the ablation and etching of the surface of solid polymethyl methacrylate. The reaction which is termed ’ablative photodecomposition’ results in the break up of the polymer chains to oligomers of much lower molecular weight along with the production of gases such as C2, CO, CO2, and the monomer, methyl methacrylate. The gaseous products are ejected from the surface at supersonic velocities and carry the solid particles of the polymer along. In recent work, the ablation process has been probed by imaging the surface of the polymer as well as the plume by a second laser which produced short, visible pulses and which was fired at a preset time interval after the first laser. © 1990 IUPAC