Printable version - NT-MDT

NT NEWS
NT-MDT in the USA
News Letter # 3, January 2015
AFM/Raman instrument
based on NTEGRA Spectra
(NT-MDT) scanning probe
microscope and Thermo
Scientific™ DXR™ Raman
microscope.
Combining AFM with Raman:
NT-MDT and Thermo Fisher Scientific
Quantitative Nanomechanics with
HybriD™ Mode
Since last year the joint efforts of NT-MDT and
Thermo Fisher Scientific, one of the main
manufacturers of scientific instrumentation in the
world, have led to the development of the
combined AFM/Raman instrument (see the photo
above) capable of simultaneous recording of AFM
images and Raman maps at specific wavebands,
including tip-enhanced Raman spectroscopy
experiments. The capabilities of this instrument
were verified in a number of studies of various
materials and the collected data were presented in
the Application Note: “Characterization of Materials
with a Combined AFM/Raman Microscope” and
were reported in the latest NT-MDT Webinar on
January 12. Currently, there is a series of
coordinated engineering, application, marketing
and sales efforts from both companies for the
successful promotion of the instrument in the USA
and worldwide.
Local nanomechanical studies are an essential
capability of AFM, which can be realized in contact
mode and oscillatory resonant and non-resonant
modes. The elastic modulus and work of adhesion
can be extracted from the force curves. It is done
most efficiently in the HybriDТМ mode where the
quantitative maps of these properties can be
obtained on-line simultaneously with the height
images. The validity of the quantitative
measurements is verified on the test set of neat
polymer samples (polystyrene and two different
polyethylenes) with macroscopic Young modulus in
the range from tens of MPa to several GPa. We are
exploring this functionality in depth, and in case of
heterogeneous samples we have achieved the
mapping of the elastic modulus at the sub-100 nm
scale. The illustration of the high-resolution
modulus mapping is given by the elastic modulus
map (512512) of high-density polyethylene
(HDPE), see below. In this picture an amorphous
interlamellar layer of 10 nm in width is clearly seen
in the map and in the related cross-section.
Map of elastic
modulus of HDPE
sample. A crosssection along the
white dashed line
is shown below.
More examples of high-resolution mapping of
mechanical properties of polymers will be shown in
the upcoming NT-MDT Webinar on February 12.
In another approach to local nanomechanical
properties, we are exploring the use of amplitudeversus-distance curves, which are recorded in
amplitude modulation mode. The analysis of these
curves in terms of solid state deformation models is
complicated due to a non-trivial relation between
amplitude/phase and the tip-sample forces. The
problem can be solved as shown in our research
paper “Modeling and Measurements in Atomic
Force Microscopy Resonance Modes” by S. Belikov
et al, which is accepted for publication at American
Control Conference, 2015. The experimental
verification of these calculations is on the way.
“inverted” pyramids are shown in the second 3D
height image. The cross-section profiles reveal the
height corrugations in the 6-8 microns range. The
precise evaluation of the sample topography of
these black Si samples and its correlation with light
trapping is important for improving the solar cell
efficiency.
Height image of black
Si sample. The crosssection profile along
the white dashed line
is shown underneath.
3D height image
(40 m) of a model
Si sample. The
cross-section
profile along the
horizontal diagonal
is shown
underneath.
From the Laboratories
In Tempe office, we appreciate greatly the requests
of the researchers regarding different capabilities of
our AFM microscopes, and we are happy to help
them by evaluating their samples. In one of such
interactions with Salman Manzoor (Holman Lab,
ASU) we have been challenged by an examination
of Si profiles of several microns in height. Such
profiles are essential features of black Si – the lightharvesting element of solar panels. We have
performed these measurements with Titanium
scanning probe microscope using the high-aspect
ratio probes with single crystal diamond tips. Two
examples of these studies are given below. The first
height image shows the Si pyramids, and the
Forthcoming NT-MDT Events:
February 12: Webinar “High-Resolution and
Quantitative Mapping of Mechanical Properties”,
which is based on studies of elastic modulus and
work of adhesion of polymers in the HybriDТМ
mode.
Register at:
https://attendee.gotowebinar.com/register/6919014831
885373698 Webinar ID: 123-101-859
February 19-20: NT-MDT AFM/Raman Workshop at
Carnegie Mellon University (Pittsburgh, PA), which
includes technical presentations and demonstration
sessions using NT-MDT microscopes. Further info:
[email protected]_america.com