XPS and QCM Studies of Hydrocarbon and Fluorocarbon Polymer Films Bombarded by 1−20 keV C60 Ions

Abstract

Poly(methyl methacrylate) or PMMA, Teflon AF1600, and poly(3-hexylthiophene) films are studied after bombardment with different fluences of C60 ions with energies of 1−20 keV by a quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS). C 1s XP spectra show little or no change in the film chemistry upon ion bombardment up to 1013−1014 ions/cm2. This result supports prior observations from secondary ion yields that at least some organic films have no apparent static limit in secondary ion mass spectrometry (SIMS) using C60 ion projectiles until the film is sputtered away. Changes in C 1s XP spectra observed at the highest ion energies and fluences >1015 ions/cm2 are explained predominantly by differential charging effects. Some changes in film composition are also observed, but their extent varies with the polymer studied. Measurements for the total sputter yield of films acquired using a QCM show that each C60 cluster leads to an efficient emission of ∼105 amu per C60 ion at 20 keV im...