title: Probing viscoelastic response of soft material surfaces at the nanoscale.
abstract: We study the interaction between an AFM tip and a soft viscoelastic surface. Using a multifrequency method we measure the amplitude-dependence of the cantilever dynamic force quadratures, which clearly show the effect of finite relaxation time of the viscoelastic surface. A model is introduced which treats the tip and surface as a two-body dynamic problem with a nonlinear interaction depending on their separation. We find good agreement between simulations of this model and experimental data on polymer blend samples for a variety of materials and measurement conditions.
authors.affiliation: Nanostructure Physics and Nordita, Royal Institute of Technology (KTH), Roslagstullsbacken 21, SE-10691 Stockholm, Sweden. haviland@kth.se.
authors.forename: David B
authors.initials: DB
authors.lastname: Haviland
authors.forename: Cornelius Anthony
authors.initials: CA
authors.lastname: van Eysden
authors.forename: Daniel
authors.initials: D
authors.lastname: Forchheimer
authors.forename: Daniel
authors.initials: D
authors.lastname: Platz
authors.forename: Hailu G
authors.initials: HG
authors.lastname: Kassa
authors.forename: Philippe
authors.initials: P
authors.lastname: Leclère