title: High-resolution dynamic atomic force microscopy in liquids with different feedback architectures.
abstract: The recent achievement of atomic resolution with dynamic atomic force microscopy (dAFM) [Fukuma et al., Appl. Phys. Lett. 2005, 87, 034101], where quality factors of the oscillating probe are inherently low, challenges some accepted beliefs concerning sensitivity and resolution in dAFM imaging modes. Through analysis and experiment we study the performance metrics for high-resolution imaging with dAFM in liquid media with amplitude modulation (AM), frequency modulation (FM) and drive-amplitude modulation (DAM) imaging modes. We find that while the quality factors of dAFM probes may deviate by several orders of magnitude between vacuum and liquid media, their sensitivity to tip-sample forces can be remarkable similar. Furthermore, the reduction in noncontact forces and quality factors in liquids diminishes the role of feedback control in achieving high-resolution images. The theoretical findings are supported by atomic-resolution images of mica in water acquired with AM, FM and DAM under similar operating conditions.
authors.affiliation: Department of Engineering Mathematics, University of Bristol, Bristol BS8 1TR, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Melcher
authors.forename: David
authors.initials: D
authors.lastname: Martínez-Martín
authors.forename: Miriam
authors.initials: M
authors.lastname: Jaafar
authors.forename: Julio
authors.initials: J
authors.lastname: Gómez-Herrero
authors.forename: Arvind
authors.initials: A
authors.lastname: Raman
keywords: atomic force microscopy; dAFM; high-resolution; liquids