title: Quartz tuning fork-based frequency modulation atomic force spectroscopy and microscopy with all digital phase-locked loop.
abstract: We present a platform for the quartz tuning fork (QTF)-based, frequency modulation atomic force microscopy (FM-AFM) system for quantitative study of the mechanical or topographical properties of nanoscale materials, such as the nano-sized water bridge formed between the quartz tip (~100 nm curvature) and the mica substrate. A thermally stable, all digital phase-locked loop is used to detect the small frequency shift of the QTF signal resulting from the nanomaterial-mediated interactions. The proposed and demonstrated novel FM-AFM technique provides high experimental sensitivity in the measurement of the viscoelastic forces associated with the confined nano-water meniscus, short response time, and insensitivity to amplitude noise, which are essential for precision dynamic force spectroscopy and microscopy.
authors.affiliation: Center for Nano-Liquid, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, South Korea.
authors.forename: Sangmin
authors.initials: S
authors.lastname: An
authors.forename: Mun-heon
authors.initials: MH
authors.lastname: Hong
authors.forename: Jongwoo
authors.initials: J
authors.lastname: Kim
authors.forename: Soyoung
authors.initials: S
authors.lastname: Kwon
authors.forename: Kunyoung
authors.initials: K
authors.lastname: Lee
authors.forename: Manhee
authors.initials: M
authors.lastname: Lee
authors.forename: Wonho
authors.initials: W
authors.lastname: Jhe