title: Determining cantilever stiffness from thermal noise.
abstract: We critically discuss the extraction of intrinsic cantilever properties, namely eigenfrequency f n , quality factor Q n and specifically the stiffness k n of the nth cantilever oscillation mode from thermal noise by an analysis of the power spectral density of displacement fluctuations of the cantilever in contact with a thermal bath. The practical applicability of this approach is demonstrated for several cantilevers with eigenfrequencies ranging from 50 kHz to 2 MHz. As such an analysis requires a sophisticated spectral analysis, we introduce a new method to determine k n from a spectral analysis of the demodulated oscillation signal of the excited cantilever that can be performed in the frequency range of 10 Hz to 1 kHz regardless of the eigenfrequency of the cantilever. We demonstrate that the latter method is in particular useful for noncontact atomic force microscopy (NC-AFM) where the required simple instrumentation for spectral analysis is available in most experimental systems.
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany.
authors.forename: Jannis
authors.initials: J
authors.lastname: Lübbe
authors.forename: Matthias
authors.initials: M
authors.lastname: Temmen
authors.forename: Philipp
authors.initials: P
authors.lastname: Rahe
authors.forename: Angelika
authors.initials: A
authors.lastname: Kühnle
authors.forename: Michael
authors.initials: M
authors.lastname: Reichling
keywords: AFM; Q-factor; cantilever; noncontact atomic force microscopy (NC-AFM); resonance; spectral analysis; stiffness; thermal excitation