<mailto:sarioglu@stanford.edu>
Title: Time-resolved Tapping-mode Atomic Force Microscopy
Date: Friday, July 24, 2009
Time: 3:45 pm (Refreshments at 3:30 pm)
Location: Packard Room 101
Abstract:
There is an increasing interest in the use of atomic force microscopy
(AFM) for quantitative mapping of material specific surface properties.
However, methods that have been developed for local stiffness
measurements generally suffer from low operational speeds and they apply
large forces to the surface limiting their resolution and use on soft
materials such as polymers and biological samples. On the other hand,
tapping-mode AFM, which is well suited to soft materials due to its
gentle interaction with the surface, cannot be used to recover
information on the tip-sample interaction (and hence, on the material
properties) due to limited bandwidth of the AFM probe.
In this talk, a technique for rapid quantitative material
characterization with nanoscale spatial resolution will be introduced.
This technique is based on time-resolved measurement of tip-sample
interaction forces during tapping-mode AFM imaging by a special
micromachined AFM probe. In this probe, a high-bandwidth interferometric
force sensor at the end of the cantilever is coupled to the tip motion
and is used to resolve tip-sample interaction forces with high
sensitivity and temporal resolution. Combined with a real-time signal
processing software that we developed, these probes provide quantitative
maps of peak interaction forces and elastic properties simultaneously
with conventional AFM data. High-contrast compositional mapping,
quantitative peak force imaging and quantitative material
characterization by mapping surface Young's modulus acquired using this
system will be demonstrated on various samples.
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