exploring different atomic force microscopy probes...exploring different atomic force microscopy...
TRANSCRIPT
Exploring Different Atomic Force Microscopy Probes
Sergei Magonov
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Outline
1. Regular and High-Resolution AFM Probes
2. Approaching True Molecular/Atomic Resolution in AFM
3. AFM Probes for Measurements of Local Mechanical, Electric and Thermal Properties
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Regular and High-Resolution Silicon ProbesRegular Si Probes
Carbon Spike Tungsten SpikeCNT-Probes
High-Resolution Probes
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Bottom images – courtesy of MikroMasch
Carbon SpikeSi waferRegular Si tip
Effect of Tip Sharpness in Imaging of Nanoscale Structures
10 nm 1 3 nm10 nm 1-3 nm
RNA-Based NanostructuresRegular Si tip Carbon Spike
Cooperation with A
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150 nm150 nmCooperation with A. Koyfman (UCSB)
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Polydiacetylene crystal, PDA TY
Contact mode in airMolecular Resolution in Atomic Force Microscopy
T2TX
Y
Magonov S et al Polym
bc Tx
Ty
0.49 c 1.41
Magonov S. et al Polym. Bull. 1991, 26, 223
nm1.41 nm 8.5 nm
Si (7×7) F. Giessibl, Science 1995, 267, 68
Frequency Modulation in UHV, air, liquid
H. Yamada group (Kyoto University) PDASAMY. Sugawara et al Science 1995, 270, 1646
6
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5.5 nm6 nm
APL 2005, 86, 034101; 193108
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Molecular Resolution in Atomic Force Microscopy
Amplitude Modulation i i
Polydiacetylene crystal, PDA
in air
Veeco D5000 +
D. Klinov, S. Magonov APL 2004, 84, 2697
20 nm 15 nmNSIIIA/Extender
Amplitude Modulation in air
Polydiacetylene crystal, PDA
Agilent 5500 microscope
15 nmLow thermal drift of AFM microscope is the key feature for high-resolution
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microscope23 nm
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y gimaging in amplitude modulation mode.
Simulation of Imaging of PDA in Amplitude Modulation Mode
Low-force imaging of the
R = 0.15 nm R = 5 nm R = 100 nm
Low force imaging of the perfect PDA lattice with tips of different size (R – radius)
corrugations ~ 0.01 nmcorrugations ~ 0.03 nmcorrugations ~ 0.2 nm
Imaging of the perfect PDA lattice with a tip (R = 5 nm)
Force increases (Asp decreases) ->
at different set levels of tip-sample force (different set-point amplitudes, Asp)
Imaging of the defect PDA lattice with tips of different i (R) d diff t f
R = 0.15nm; Asp = 20 nm R = 1nm; Asp = 19 nm R = 5nm; Asp = 18 nm
S. Belikov & S. Magonov, Jap J Appl Phys 45 (2006) 2158;
size (R) and different forces (Asp).
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S. Magonov & S. Belikov www.nanohub.org/resources/2030/
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1 2 4Single diamond probe before imaging After AFM imagingImaging of etched Al
Optimization of Imaging in Oscillatory Mode: Wear of Tip Apex
1 2 4
MicroStar
3R3=10nm
Si probe before imaging After imaging polymer (E~2GPa) After imaging etched Al
TechnologiesR3=14nm
Cooperation ith Bernard Mesa
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Probe stiffness k=0.6 N/mCooperation with Bernard Mesa (MicroStar Technologies)
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Team-Nanotec
Effect of Tip Sharpness in Imaging of Nanoscale Structures
T N t
Olympus Team-Nanotec
Team-Nanotec
Sharp probe Spherical probe
76 nm10 nm
34 nm 35 nm
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1 μm 1 μm
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Electrochemically etched Pt/Ir probe Mechanically sharpened Pt/Ir probe Sharpened Pt/Ir probe (MST)Probes for Scanning Tunneling Microscopy
Probes for Electric Measurements in Scanning Probe Microscopy
Commercial SiO2 with Pt coating Conducting Single Diamond Probe (MST)Probes for Electric Force Microscopy
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MST – MicroStar Technologies
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Electric Force Microscopy with Diamond/Sapphire ProbesSingle diamond tip
S hiSapphire cantilever
Conducting Si probe Conducting diamond probe
1. A sapphire cantilever with a semi-circular cross-section eliminates optical interference common for commercial
Mesa B Magonov S J Physics
probes.
2. Long diamond tip (~100 μm) reduces damping of Q-factor.
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Mesa B., Magonov S. J. Physics Conf Ser 2007, 61, 770
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Micromachined Thermal Probes
Introduction to Nano-TA
Infrared Microscopy
200 μm200 μm
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Courtesy of Kevin Kjoller (Anasys Instruments)
AFM Probe for Measurements of Time-Varying Nanomechanical Forces Flexural Vibration
Spectrum Torsional Response
Flexural Response
Torsional Vibrational Spectrum
Force-vs.-Time
1. Imaging at high harmonicsForce-vs.-Distance
Topography Phase 10th Harmonic
85C
2. Mapping of mechanical properties during scanning in amplitude modulation mode
115C
Height Phase
7 μm
Elastic modulus145C
160C
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O. Sahin et al Nature Nanotechnology 2007, 226, 1038.
ConclusionsLow-force imaging with atomic-size probes is the ultimate goal of AFMLow-force imaging with atomic-size probes is the ultimate goal of AFM because it provides true sample topography and true molecular/atomic resolution. At the moment, limitations of the tip-force control and tip sharpness restrict image resolution. Joint efforts of instrument and probesharpness restrict image resolution. Joint efforts of instrument and probe developers are needed for further progress in high-resolution imaging.
In practical purposes, a characterization of AFM probe (performed by a probe manufacturer or by user) is invaluable for their optimal choice thatprobe manufacturer or by user) is invaluable for their optimal choice that depends on a particular application. For many applications, probes with a round-shaped tip (with known and not necessary small diameter) might be more rational than a use of sharp probesmore rational than a use of sharp probes.
AFM value is also increasing due to expanded capabilities of mapping mechanical, electric and thermal properties. These applications require a large variety of the probes in which specific properties should be in interplaylarge variety of the probes, in which specific properties should be in interplay with the cantilever and tip geometries, and this field demands increasing attention.
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