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Beilstein J Nanotechnol. 2012; 3: 336–344.
Published online Apr 18, 2012. doi:  10.3762/bjnano.3.38
PMCID: PMC3343270
Drive-amplitude-modulation atomic force microscopy: From vacuum to liquids
Miriam Jaafar,1 David Martínez-Martín,corresponding author1 Mariano Cuenca,2 John Melcher,3 Arvind Raman,4 and Julio Gómez-Herrerocorresponding author1
Udo D Schwarz, Guest Editor
1Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
2Servicios generales de apoyo a la investigación, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
3Department of Engineering Mathematics, University of Bristol, Bristol BS8 1TR, United Kingdom
4Birck Nanotechnology Center and School of Mechanical Engineering, Purdue University, West Lafayette, IN 47904-2088, USA
corresponding authorCorresponding author.
David Martínez-Martín: davidmmo/at/gmail.com; Julio Gómez-Herrero: julio.gomez/at/uam.es
Received January 20, 2012; Accepted March 15, 2012.
Summary
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.
Keywords: atomic force microscopy, control systems, dissipation, frequency modulation, noncontact
Abstract
A mathematical equation, expression, or formula.
 Object name is Beilstein_J_Nanotechnol-03-336-g001.jpg
Keywords: atomic force microscopy, control systems, dissipation, frequency modulation, noncontact
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