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MAGNETICALLY ACTIVATED DYNAMIC (MAD) MODE AFM
By placing a magnetic particle directly behind the AFM tip we are able to apply forces to the probe via a magnetic field. It is then possible to vibrate the probe well below resonance in an oscillating magnetic field in order to directly measure the force gradient of the tip-sample interaction. We have extended this method of activation to make the resonance method of FM detection possible. This is better suited for high-resolution imaging in the liquid environment compared to the off resonance method because faster imaging is possible and this reduces problems associated with thermal drift. Although previously only used in ultra-high vacuum, by implementing the MAD-mode for driving the oscillation we have been able to remove unwanted resonances in the rest of our liquid cell which can occur with alternative driving methods. This is illustrated in the figures below.
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(a) When measuring the acoustically excited cantilever response, it is difficult to distinguish the resonance peak corresponding to the cantilever. Numerous unwanted peaks that mask the actual resonance peak are observed due to vibration of the liquid cell.
(b) The measured cantilever response (solid line) in MAD mode is the same as the actual resonance frequency (dashed line). A single resonance peak is observed. |
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S. P. Jarvis, T. P. Weihs, A. Oral and J. B. Pethica, "Mechanics of contacts at less than 100Å scale: indentation and AFM", Thin Films - Stresses and Mechanical Properties IV , Mater. Res. Soc. Proc. 308 (1993) 127. |
S. P. Jarvis, A. Oral, T. P. Weihs and J. B. Pethica, "A novel force microscope and point contact probe", Rev. Sci. Inst. 64 (1993) 3515. |
S. P. Jarvis and J. B. Pethica, "Hydrophobic surface interactions studied using a novel force microscope", in Forces in Scanning Probe Methods , NATO ASI series E: Applied Sciences, Kluwer Academic Publishers. Eds. D.Anselmetti & E.Meyer. p.105. |
S. P. Jarvis and J. B. Pethica, "Comparison of hydrophobic modifying layers on SiO 2 studied with force controlled AFM", Thin Solid Films, 273 (1996) 284-288. |
S. P. Jarvis, H. Yamada, S.-I. Yamamoto and H. Tokumoto "A new force controlled atomic force microscope for use in ultrahigh vacuum", Rev. Sci. Instrum. 67 , 2281 (1996). |
S. P. Jarvis, H. Yamada, S.-I. Yamamoto, H. Tokumoto and J. B. Pethica "Direct mechanical measurement of interatomic potentials", Nature 384 , 247 (1996). |
S-.I. Yamamoto, H. Yamada, S. P. Jarvis, M. Motomatsu and H. Tokumoto "Detection of similar elastic properties using a magnetic force controlled AFM", Thin Films - Stresses and Mechanical Properties VI, Mater. Res. Soc. Proc. 436 , 385 (1997). |
S. P. Jarvis, S.-I. Yamamoto, H. Yamada, H. Tokumoto and J. B. Pethica "Tip-Surface Interactions Studied Using a Force Controlled Atomic Force Microscope in Ultra High Vacuum", Appl. Phys. Lett. 70 , 2238 (1997). |
S. P. Jarvis, U. Dürig, M. A. Lantz, H. Yamada and H. Tokumoto "Feedback stabilized force-sensors: A gateway to the direct measurement of interaction potentials", Applied Physics A, 66 , S211 (1998). |
S. P. Jarvis, M. A. Lantz, U. Dürig and H. Tokumoto, "Off resonance ac mode force spectroscopy and imaging with an atomic force microscope", Appl. Surf. Sci. 140 , 309 (1999). |
S. P. Jarvis, M. A. Lantz, H. Ogiso, H. Tokumoto and U. Dürig "Conduction and Mechanical Properties of Atomic Scale Gold Contacts", Appl. Phys. Lett., 75 , 3132 (1999). |
S. P. Jarvis, H. Tokumoto, H. Yamada, K. Kobayashi and A. Toda "An alternative method for the activation and measurement of lateral forces using magnetically controlled atomic force microscopy", Appl. Phys. Lett., 75 , 3883 (1999). |
M. A. Lantz, S. P. Jarvis, H. Tokumoto, T. Martynski, T. Kusumi, C. Nakamura and J. Miyake "Stretching the a-helix - A direct measure of the hydrogen bond energy of a single peptide molecule", Chem. Phys. Lett., 315 , 61 (1999). |
S. P. Jarvis, H. Yamada, K. Kobayashi, A. Toda and H. Tokumoto, "Normal and Lateral Force Investigation using Magnetically Activated Force Sensors", Appl. Surf. Sci., 157 , 314 (2000). |
S. P. Jarvis, T. Uchihashi, T. Ishida, H. Tokumoto and Y. Nakayama, "Local Solvation Shell Measurement in Water using a Carbon Nanotube Probe", J. Phys. Chem. B, 26 , 6091 (2000). |
S. P. Jarvis, T. Ishida, T. Uchihashi, Y. Nakayama and H. Tokumoto, "Frequency modulation detection Atomic Force Microscopy in the Liquid Environment", Applied Physics A, 72 , S129-S132 (2001). |
M. Kageshima, M. A. Lantz, S. P. Jarvis, H. Tokumoto, S. Takeda, A. Ptak, C. Nakamura, J. Miyake "Insight into conformational changes of a single A-helix peptide molecule through stiffness measurements", Chem. Phys. Lett., 343 , 77-82 (2001). |
A. Ptak, S. Takeda, C. Nakamura, J. Miyake, M. Kageshima, S. P. Jarvis and H. Tokumoto "A modified atomic force microscope applied to the measurement of elastic modulus for a single peptide molecule", J. Appl. Phys., 90 , 3095-3099 (2001). |
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