Laser ablation of polymethylmethacrylate and polystyrene at 308 nm: Demonstration of thermal and photothermal mechanisms by a time-of-flight mass spectroscopic study

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Abstract
Laser ablation of polymethylmethacrylate and polystyrene films by an excimer laser at 308 nm was studied by detecting the fragments by time-of-flight mass spectroscopy after multiphoton ionization. Neutral fragments ablating from the polymer surface were predominantly monomer and dimer methylmethacrylate and monomer styrene, as deduced from the mass spectra. Thus, ‘‘unzipping’’ of these polymers occurs. The dependence of fragment yields on ablating laser fluence and kinetic energy distributions of ablating species demonstrates thermal and photothermal dissociation of these polymers under the experimental conditions.