title: Virtual resonance and frequency difference generation by van der Waals interaction.
abstract: The ability to explore the interior of materials for the presence of inhomogeneities was recently demonstrated by mode synthesizing atomic force microscopy [L. Tetard, A. Passian, and T. Thundat, Nature Nanotech. 5, 105 (2009).]. Proposing a semiempirical nonlinear force, we show that difference frequency ω_ generation, regarded as the simplest synthesized mode, occurs optimally when the force is tuned to van der Waals form. From a parametric study of the probe-sample excitation, we show that the predicted ω_ oscillation agrees well with experiments. We then introduce the concept of virtual resonance to show that probe oscillations at ω_ can efficiently be enhanced.
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6123, USA.
authors.forename: L
authors.initials: L
authors.lastname: Tetard
authors.forename: A
authors.initials: A
authors.lastname: Passian
authors.forename: S
authors.initials: S
authors.lastname: Eslami
authors.forename: N
authors.initials: N
authors.lastname: Jalili
authors.forename: R H
authors.initials: RH
authors.lastname: Farahi
authors.forename: T
authors.initials: T
authors.lastname: Thundat
mesh_terms: D000818:Animals; D002473:Cell Wall / Q000737:chemistry; D008031:Lignin / Q000737:chemistry*; D008322:Mammals / Q000502:physiology*; D018625:Microscopy, Atomic Force; D008956:Models, Chemical; D017711:Nonlinear Dynamics; D059828:Plant Cells; D010944:Plants / Q000737:chemistry / Q000378:metabolism*; D013499:Surface Properties
chemical_list: C036909:lignocellulose; D008031:Lignin