page_title: Non-contact atomic force microscopy
hierarchical_section_title: Non-contact atomic force microscopy
caption_attribution_description: Top: Constant height non-contact atomic force microscopy image of a hydrogen-bonded naphthalene tetracarboxylic diimide (NTCDI) island on the Ag:Si(111)-(√3 x √3) R30° surface acquired at 77 K. Image size 2.1 by 2.0 nm (oscillation amplitude, 275 pm). Bottom: model (Colour coding: grey, carbon; white, hydrogen; red, oxygen; blue, nitrogen)
context_page_description: Non-contact atomic force microscopy, also known as dynamic force microscopy, is a mode of atomic force microscopy, which itself is a type of scanning probe microscopy. In nc-AFM a sharp probe is moved close to the surface under study, the probe is then raster scanned across the surface, the image is then constructed from the force interactions during the scan. The probe is connected to a resonator, usually a silicon cantilever or a quartz crystal resonator. During measurements the sensor is driven so that it oscillates. The force interactions are measured either by measuring the change in amplitude of the oscillation at a constant frequency just off resonance or by measuring the change in resonant frequency directly using a feedback circuit to always drive the sensor on resonance.
context_section_description: Non-contact atomic force microscopy (nc-AFM), also known as dynamic force microscopy (DFM), is a mode of atomic force microscopy, which itself is a type of scanning probe microscopy. In nc-AFM a sharp probe is moved close (order of Angstroms) to the surface under study, the probe is then raster scanned across the surface, the image is then constructed from the force interactions during the scan. The probe is connected to a resonator, usually a silicon cantilever or a quartz crystal resonator. During measurements the sensor is driven so that it oscillates. The force interactions are measured either by measuring the change in amplitude of the oscillation at a constant frequency just off resonance (amplitude modulation) or by measuring the change in resonant frequency directly using a feedback circuit (usually a phase-locked loop) to always drive the sensor on resonance (frequency modulation).
caption: DFM image of napthalenetetracarboxylic diimide molecules on silver interacting via hydrogen bonding (77 K). Image size 2×2 nm. Bottom image shows atomic model (colors: grey, carbon; white, hydrogen; red, oxygen; blue, nitrogen).[1]
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