Nanometer-nanosecond dynamics in laser-induced expansion/contraction and ablation of polymer films

Abstract

In this account we have summarized our systematic studies on laser ablation and related phenomena of polymer films by utilizing time-resolved absorption spectroscopy and nanosecond interferometry. Polystyrene, poly(methyl methacrylate), poly(methyl acrylate), azobenzene-substituted urethane-urea copolymer, nitrocellulose, triazene polymer, polyurethane, and polyimide were examined, and their expansion and contraction dynamics were confirmed directly at the laser fluence below the ablation threshold. The molecular species which are formed by intense laser excitation are identified by absorption spectroscopy and correlated to the morphological changes. We proposed the cyclic multiphotonic absorption mechanism and explained well the ablation and related phenomena In terms of photophysics and photochemistry.