Enhancing Sensitivity of Atomic Force Microscopy for Characterization of Surface Chemical Heterogeneity.
Enhancing Sensitivity of Atomic Force Microscopy for
Characterization of Surface Chemical Heterogeneity.
Gu, X.; VanLandingham, M. R.; Fasolka, M.; Martin, J.
W.; Jean, J. Y.; Nguyen, T.
Adhesion Fundamentals: From Moecules to Mechanisms and
Modeling. Annual Meeting of the Adhesion Society, 26th.
Proceedings. February 23-26, 2003, Myrtle Beack, SC,
Koberstein, J. T.; Anderson, G. L., Editor(s)(s),
185-187 pp, 2003.
microscopy; nanoscale; chemical heterogeneity; humidity
chamber; phase contrast
Atomic force microscopy (AFM) has played an increasingly
important role in characterizing surface morphology and
surface properties of materials. However, the ability to
identify and map the surface chemical heterogeneity has
remained an unfulfilled opportunity in the field of AFM.
Chemical force microscopy (CFM) is a successful approach
for enhancing the chemical sensitivity of AFM. However,
CFM has usually been conducted in liquid instead of air
to eliminate capillary effects. In our study, a
well-controlled humidity system is used to enhance the
sensitivity of AFM in characterizing surface chemical
heterogeneity. The relative humidity (RH) of the
tip-sample environment is controlled using a humidity
generator and a novel small-volume environmental chamber
designed and fabricated at the National Institute of
Standards and Technology. The relative humidity in the
chamber can be controlled from nearly 0% RH up to 95%
RH. The effects of RH on AFM image contrast are studied
using a patterned SAM sample and polymers with
alternating regions of hydrophobic and hydrophilic
materials. The results clearly demonstrate that the
image contrast between hydrophilic and hydrophobic
regions of a surface is substantially increased in
elevated relative humidity environments.