ArF (193 nm) laser ablation of poly(methyl methacrylate)

We report results from a range of complementary studies of pulsed ArF (193 nm) laser ablation of poly (methyl-methacrylate), PMMA, in vacuo, and in th e presence of low background pressures of Ar and He, designed to identify c orrelations between the properties of the plume and those of the a-C:H film s that result when the plume is incident on a NaCl substrate. The plume its elf has been investigated by wavelength, spatially and/or temporally resolv ed measurements of the emission from electronically excited H*, C* O*, CH* and C-2* fragments, and by Langmuir probe (time-of-flight) measurements of the positively and negatively charged ablated particles, as a function of l aser fluence and of ambient gas pressure. Infrared absorption spectroscopy suggests that a-C:H films deposited following pulsed laser ablation of PMMA under low pressures of Ar contain similar C:H:O ratios to the parent polym er, but also confirms previous reports that films deposited in vacuo have a reduced H content. (C) 1999 Elsevier Science S.A. All rights reserved.