Subsurface Imaging of the Cores of Polymer-Encapsulated Cobalt Nanoparticles Using Force Modulation Microscopy

Stephen M. Deese, Lauren E. Englade-Franklin, Lawrence J. Hill, Jeffrey Pyun, Julia Y. Chan, Jayne C. Garno

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Force modulation microscopy (FMM) is a mode of scanning probe microscopy that can be used to visualize changes of tip-sample interactions for hard and soft areas of samples such as polymers and organic thin films. In designed experiments, polystyrene-encapsulated cobalt nanoparticles were imaged with FMM using a home-built sample stage for sample actuation. Regions of the outer polymer coating and the inner cobalt nanoparticle were resolved with high resolution. Using FMM, differences in the elastic and viscoelastic properties of the nanoparticles were visualized with nanoscale resolution by monitoring the return amplitude and phase signals as the AFM tip is scanned over areas of a sample. Regions of the sample with greater elasticity and viscoelasticity generate a weaker signal relative to harder areas because more of the energy associated with the cantilever oscillation is dissipated by the material. Areas with greater elasticity will tend to absorb more of the energy of the cantilever causing the amplitude of the oscillation to be dampened. Conversely, harder areas, having a lower elasticity, will cause the tip to oscillate closer to the input driving amplitude of the piezoceramic. The polymer-encapsulated nanoparticles were patterned using two-particle lithography to prevent aggregation of the nanoparticles.

Original languageEnglish (US)
Pages (from-to)23498-23504
Number of pages7
JournalJournal of Physical Chemistry C
Issue number42
StatePublished - Oct 26 2017

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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