AVS 53rd International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeM

Paper AS-WeM4
XPS and QCM Studies of PMMA and Teflon AF1600 Films Bombarded by 1-20 keV C@sub 60@@super +@ Ions

Wednesday, November 15, 2006, 9:00 am, Room 2005

Session: Molecular Ion Sources and Characterization of Biomaterials
Presenter: L. Hanley, University of Illinois at Chicago
Authors: I.L. Bolotin, University of Illinois at Chicago
S.H. Tetzler, University of Illinois at Chicago
L. Hanley, University of Illinois at Chicago
Correspondent: Click to Email
keV C@sub 60@ ions are widely used as projectiles in secondary ion mass spectrometry of polymeric materials. Evidence exists that the mechanism of sputtering by C@sub 60@ ions allows their use for damage-free depth profiling. Surface analysis studies are presented to probe absolute sputtering yields and surface modification of two polymer films by C@sub 60@ ions. Polymethylmethacrylate (PMMA) and Teflon AF1600 spin-casting films studied during different bombardment doses of C@sub 60@ ions with energies of 1-20 keV by quartz-crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS) . Measurements for the total sputter yield of films are acquired using a QCM. Mass-lost rate data show that each 20 keV C@sub 60@ cluster leads to emission ~10@super 6@ amu of polymer, indicating that the non-overlapping crater regime exists for doses of <10@super 12@ ion/cm@super 2@. Sputtering yields of these polymer films are ~5 higher than those of polycrystalline gold films at >10 keV. Chemical modification is also probed by XPS of the target surface before and after ion bombardment. Both polymers display little to no damage to their film structure at ion fluences below ~10@super 13@ ion/cm@super 2@. Changes in C 1s XPS spectra during higher fluence bombardment can be explained predominantly by differential charging effects. However, ion fluences >10@super 15@ ion/cm@super 2@ modify the film composition to a carbon-rich material with various degradation products.