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Atomic Force Microscope
Vecco Dimension 3100
(supported by Bruker)
Location White Bldg.
Room 613
Atomic Force Microscope
AFM Control unit and software
Atomic Force Microscope
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Atomic Force Microscope Components
(S)canning (P)robe (M)icroscope head
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Stage holder and (2) types of tips
1. Tapping
2. Contact
3. Magnetic (not shown)
Atomic Force Microscope Tips
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Tapping tip on holder.
Zoom in on tip.
Typical Silicon Tips
5-20 nm tip radii
20-100 N/m stiffness
www.brukerafmprobes.com
Atomic Force Microscope Tips
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Contact tip on holder.
Important to match the stiffness of the
tip to the sample being measured.
Zoom in
on tip.
www.brukerafmprobes.com
Atomic Force Microscope Simplistic Operation
Click to play
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Example of AFM measurements – Tapping Mode
Nanoindentation – Optical image
Nitinol material
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AFM scan - 30 um x 30 um
Nitinol material – Limitations of scan 100 um x 4.8 um deep
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AFM scan - 30 um x 30 um – isometric
Nitinol material
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AFM Geometry Analysis
Nitinol material
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AFM Geometry Analysis – Vertical Distance
Nitinol material
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AFM Geometry Analysis – Rmax
Nitinol material
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AFM Geometry Analysis – Depth of indent
Nitinol material
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AFM Geometry Analysis – Angle of indent
Nitinol material
9/9/14
Picking the right AFM Tip – Size matters
Click to play
10/27/14
Contact AFM – Force Microscopy
Understanding contamination and its effects
Click to play
• In ambient air, surface are covered with contamination
• A probe encounters contamination when approaching a
surface
• Capillary forces pull the contamination up onto the probe
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Using contact mode with Force modulation
Consider a simple case of Tip / Sample interaction
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300
200
The X & Y of the
scanner is fixed. It
moves in Z as shown
by Extension.
Deflection (nm)
100
A
0
-100
Extend
-200
-300
-400 0
Retract
500
1000
1500
2000
-500
-600
-700
Extension (nm)
Rubber sample material
2500
Van der Waals
forces can be
seen as the tip
approaches the
surface (A).
Tip / Sample interaction
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300
200
These attractive
forces pull the tip
down.
Deflection (nm)
100
A
0
-100
Point of contact (B).
B
Extend
-200
-300
-400 0
Retract
500
1000
1500
2000
-500
-600
-700
Extension (nm)
Rubber sample material
2500
Tip / Sample interaction
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300
200
C
Point of contact (B).
Deflection (nm)
100
Extension continues
and the cantilever
bends upward.
0
-100
B
Extend
-200
-300
-400 0
Retract
500
1000
1500
2000
-500
-600
-700
Extension (nm)
Rubber sample material
2500
Until (C), where the
extension stops
and so does the
deflection.
Tip / Sample interaction
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C – As the scanner
retracts, the
deflection decreases
(C to D) – red curve.
The cantilever
relaxes.
300
200
C
Deflection (nm)
100
0
-100
Extend
-200
-300
-400 0
Retract
500
1000
1500
2000
-500
-600
D
2500
There may be
surface attraction
between the tip and
sample which keeps
the tip in contact
with the surface.
-700
Extension (nm)
Rubber sample material
A monolayer of
water can also
provide this
attraction.
Tip / Sample interaction
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300
200
E – As this force is
overcome, the tip
snaps quickly back as
shown from by the
vertical trajectory
from D to E.
Deflection (nm)
100
E
0
-100
Extend
-200
-300
-400 0
Retract
500
1000
1500
2000
-500
-600
D
-700
Extension (nm)
Rubber sample material
2500
Tip / Sample interaction
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300
200
C
Force Curve Summary
Deflection (nm)
100
A
0
-100
E
B
Extend
-200
-300
-400 0
Retract
500
1000
1500
2000
-500
-600
D
-700
Extension (nm)
Rubber sample material
2500
Magnetic Force Microscopy
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Magnetic force microscopy (MFM) scans are performed using a
resonating Co-coated tip on the Bruker Dimension 3100 atomic force
microscope. Two scans are made over the same area.
The first scan determines the topology of
the surface.
The second scan is done at a fixed height
(200 nm) above the surface. Any changes
in the phase of resonance of the tip are
due to the magnetic field of the specimen.
MFM Cross-Sectional Image of a Carburized
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Duplex 2205 Stainless Steel
surface
20 mm
g
Magnetic Ferrite
Nonmagnetic Austenite: the
carbon at the surface prevents
polishing-induced martensite
Austenite with some polishinginduced Surface Martensite
(which is magnetic)
10/27/14
Thank you