Multiphoton Ionization-Mass Spectrometric Study on Laser Ablation of Polymethylmethacrylate and Polystyrene at 308 nm

Abstract

A multiphoton ionization-mass spectrometric study has been made on laser ablation of polymethylmethacrylate and polystyrene films by an excimer laser at 308 nm. “Unzipping” reactions occurred, i.e., neutral fragments ablating from the polymer surface were predominantly monomer and dimer methylmethacrylate and monomer and dimer styrene. Exponential dependence of fragment yields on ablating laser fluence and the Maxwell-Boltzmann-type velocity distributions of ablating species were found. They are due to an essentially thermal or photothermal ablation mechanism of these polymers in the experimental conditions.