11:00-12:00
Dynamic force microscopy with higher resonance mode on KBr(001)
Dr. Shigeki Kawai(Department of Physics, University of Basel, Klingelbergstr. 82, 4056 Basel Switzerland)
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After the first atomically resolved images were obtained in 1995,[1] frequency modulation dynamic force microscopy has become a reliable technique for detecting atomic scale short-range interaction. Using an FM demodulator, the resonance frequency shift caused by interaction forces can be accurately measured. However, the interpretations of such measurements are, however, complicated, and site-dependent atomic force measurements, the so-called dynamic force spectroscopy, are mandatory. Dynamic force spectroscopic measurements have been successfully demonstrated at drift-free low temperature,[2] and recently even at drift-compensated room temperature (RT).[3]
In this presentation, dynamic force spectroscopic measurements on KBr(001) at RT will be demonstrated. In order to improve the detection sensitivity, the oscillation amplitude was reduced down to several 10 pm by using higher mode techniques [4]. Setting smaller amplitude was very important to enhance the detection sensitivity not only for imaging [5] but also for dynamic force spectroscopy.[6] In small amplitude DFM, especially on a soft KBr surface, an "atomic" jump-to-contact instability, however, becomes a crucial issue. This instability was overcome with bimodal DFM [7], which is firstly applied for atomically resolved measurements.[8]
By setting an amplitude of below the ionic distance, dynamic force spectroscopy in contact was performed, and a periodic response, corresponding on each ruptures of the KBr molecular chain, was observed. A simultaneously measured cantilever deflection signal revealed a quantized spring constant of the KBr atomic chain. [9]
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[3]Y. Sugimoto, P. Pou, M. Abe, P. Jelinek, R. Perez, S. Morita,and O. Custance, Nature446, 64 (2007).
[4]S. Kawai, S. Kitamura, D. Kobayashi, S. Meguro, and H. Kawakatsu Appl. Phys. Lett. 86, 193107 (2005).
S. Kawai and H. Kawakatsu, Appl. Phys. Lett. 88, 133103 (2006).
S. Kawai and H. Kawakatsu, Phys. Rev. B 79, 115440 (2009).
[5]F. J. Giessible , H. Bielefeldt, S. Hembacher, and J. Mannhart, Appl. Surf. Sci. 140, 352 (1999).
Y. Sugimoto, S. Innami, M. Abe, O. Custance, and S. Morita, Appl. Phys. Lett. 91, 093120 (2007).
[6]S. Kawai, Th. Glatzel, S. Koch, B. Such, A. Baratoff, and E. Meyer (Submitted).
[7]T.R. Rodriguez and R. Garcia, Appl. Phys. Lett. 84, 449 (2004).
J. R. Lozano and R. Garcia, Phys. Rev. Lett.100, 076102 (2008).
[8]S. Kawai, Th. Glatzel, S. Koch, B. Such, A. Baratoff, and E. Meyer, (Submitted).
[9]S. Kawai, A. Ghasemin, Th. Glatzel, S. Koch, B. Such, A. Baratoff, S. Goedecker, and E. Meyer (In preparation).
