title: Drive-amplitude-modulation atomic force microscopy: From vacuum to liquids.
abstract: We introduce drive-amplitude-modulation atomic force microscopy as a dynamic mode with outstanding performance in all environments from vacuum to liquids. As with frequency modulation, the new mode follows a feedback scheme with two nested loops: The first keeps the cantilever oscillation amplitude constant by regulating the driving force, and the second uses the driving force as the feedback variable for topography. Additionally, a phase-locked loop can be used as a parallel feedback allowing separation of the conservative and nonconservative interactions. We describe the basis of this mode and present some examples of its performance in three different environments. Drive-amplutide modulation is a very stable, intuitive and easy to use mode that is free of the feedback instability associated with the noncontact-to-contact transition that occurs in the frequency-modulation mode.
authors.affiliation: Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
authors.forename: Miriam
authors.initials: M
authors.lastname: Jaafar
authors.forename: David
authors.initials: D
authors.lastname: Martínez-Martín
authors.forename: Mariano
authors.initials: M
authors.lastname: Cuenca
authors.forename: John
authors.initials: J
authors.lastname: Melcher
authors.forename: Arvind
authors.initials: A
authors.lastname: Raman
authors.forename: Julio
authors.initials: J
authors.lastname: Gómez-Herrero