title: Positron annihilation spectroscopy for surface and interface studies in nanoscale polymeric films.
abstract: Positron annihilation spectroscopy (PAS), coupled with a variable mono-energetic positron beam, has been used to investigate surface and interfacial properties in thin polymeric films. Free-volume properties have been measured from ortho-Positronium (o-Ps) lifetime and the S parameter of Doppler broadening of energy spectra from annihilation radiation as a function of the depth and of the temperature in thin polymeric films. Depth profiles of glass transition temperature and nanoscale layered structures in polystyrene (PS) thin films on the Si substrate are presented.
authors.affiliation: Department of Chemistry, University of Missouri-Kansas City, 5009 Rockhill Road, Kansas City, MO 64110, USA.
authors.forename: Y C
authors.initials: YC
authors.lastname: Jean
authors.forename: Junjie
authors.initials: J
authors.lastname: Zhang
authors.forename: Hongmin
authors.initials: H
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Guang
authors.initials: G
authors.lastname: Liu
mesh_terms: D004583:Electrons; D005898:Glass; D015233:Models, Statistical; D008962:Models, Theoretical; D036103:Nanotechnology; D010825:Physics / Q000379:methods*; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods*; D013499:Surface Properties; D013696:Temperature
chemical_list: D011108:Polymers; D011137:Polystyrenes