Off resonance ac mode force spectroscopy and imaging with an atomic force microscope

• Published in: Applied surface science Vol. 140; no. 3; pp. 309 - 313
• Main Authors: Jarvis, S.P., Lantz, M.A., Dürig, U., Tokumoto, H.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.1999; Elsevier Science
• Subjects: Ac mode; Atomic force microscopes; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Force control; Force spectroscopy; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Non-contact mode; Physics; Scanning probe microscopes, components and techniques; Solid surfaces and solid-solid interfaces; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Tip-surface interaction; 61.16.Ch; Force spectroscopy; 62.20.−x; Non-contact mode; Ac mode; Force control; Tip-surface interaction; 07.79.Lh; APN; Atomic force microscopy; Magnetic field effects; Tip surface interactions; Interaction potentials; Experimental study; Non contact measurement; Surface structure
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/S0169-4332(98)00546-7

Using an off resonance ac technique in ultrahigh vacuum we have directly measured the force-gradient interaction characteristics of a gold tip and sample and demonstrated a new atomic force microscope imaging mode with the tip located very close to the surface. The method involves the application of a small sinusoidal oscillating force to the tip via a magnetic field created by a conducting coil which interacts with a magnetic particle glued on the backside of the cantilever. By measuring the change in amplitude during the approach and retraction of the sample we have a continuous and accurate measure of the force gradient. The interaction potential is thus found without the need for complex analysis as is necessary in the case of the commonly used technique of measuring frequency shifts.