Laser-initiated microchemistry in thin films: development of new types of periodic structure

Decomposition of Au metallopolymer thin films induced by a scanning cw Ar+ laser leads to metallic features that, under a broad range of experimental conditions, exhibit marked periodic structure. Preliminary mechanistic studies point to a thermal decomposition pathway in which the heat released in the exothermic reaction drives the reaction front ahead of the laser-irradiated area. The spatial period is determined by laser power, scan speed, and film thickness. We argue that this mechanism is analogous to laser-initiated explosive phenomena observed in the recrystallization of amorphous semiconductors.