Dresden 2006 – scientific programme

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O: Oberflächenphysik

O 6: Scanning probe techniques I

O 6.7: Talk

Monday, March 27, 2006, 12:45–13:00, WIL B321

Using the Constant-Excitation Mode as a Spectroscopy Tool in Ambient Conditions — •Jan-Erik Schmutz, Marcus Schäfer, and Hendrik Hölscher — Center for Nanotechnology (CeNTech) and Physics Institute, University of Münster

Dynamic modes are often used in scanning force microscopy in order to improve the resolution compared to conventional contact mode. In air and liquids the so-called No-dqtapping modeNo-dq is often applied where the cantilever is oscillated with a fixed frequency near the sample surface. In vacuum, however, the so-called frequency modulation mode (FM mode) - based on a self-driven cantilever - has several advantages. Nonetheless, this technique is not limited to vacuum conditions as shown for ambient conditions and liquids. Recently, we demonstrated that the closely related constant excitation mode (CE mode) [1] allows dynamic force spectroscopy in ambient conditions [2,3]. This technique delivers not only high resolution pictures but also information about material properties like adhesion and elasticity. In difference to the tapping mode it enables the continuous measurement of the tip-sample interaction potential. Here we present an extension of this approach towards a 3D technique. By mapping systematically the frequency shift on top a single DNA strand, we created an iso-potential map of the sample potential [4]. We discuss advantages compared to conventional techniques.

[1] H. Ueyama, Y. Sugawara, S. Morita, Appl. Phys. A 66, S295 (1998). [2] H. Hölscher, B. Gotsmann, A. Schirmeisen, Phys. Rev. B 68, 153401 (2003). [3] H. Hölscher, B. Anczykowski, Surf. Sci. 579,21 (2005). [4] J.-E. Schmutz, M.M. Schäfer, H. Hölscher (submitted).