title: Step response measurement of AFM cantilever for analysis of frequency-resolved viscoelasticity.
abstract: Extension of AFM-based viscoelasticity measurement into a frequency-resolved analysis is attempted. A cantilever immersed into and interacting with distilled water was employed for the trial system. Using a home-built wideband magnetic excitation AFM, a step force with a transient time less than 1micros is applied to the AFM cantilever and its deflection is measured. The 1st and 2nd mode resonance ringing of the cantilever was suppressed using quality-factor-control technique, so that the measurement system becomes equivalent to driving a resonance-free virtual cantilever within the bandwidth limited by the surviving 3rd mode resonance. From the obtained response of the cantilever deflection, a frequency-dependent complex compliance of the cantilever-water system was derived in a frequency range of 1-100kHz. Effect of water confining between the tip and a mica substrate is discussed.
authors.affiliation: Department of Applied Physics, Graduate School of Engineering, Osaka University, Suita, Osaka, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ogawa
authors.forename: Shinkichi
authors.initials: S
authors.lastname: Kurachi
authors.forename: Masami
authors.initials: M
authors.lastname: Kageshima
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Naitoh
authors.forename: Yan Jun
authors.initials: YJ
authors.lastname: Li
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Sugawara