Asylum Research

 

Announcing the Band Excitation
Grant Winners

Matt Dawber
Stony Brook University
“Accurate and Advanced Characterization of the Piezoelectric Figures of Merit for Tailored Ferroelectric Superlattices”

Alexei Gruverman
University of Nebraska
“Band Excitation Scanning Probe Microscopy for Nanoscale Studies of Bio-organic Polymers”

Bryan Huey
University of Connecticut
“Band Excitation Methods for Novel Investigations of Phase Change Materials and Fuel Cell Systems”

Jiangyu Li
University of Washington
“Band Excitation for Quantitative Scanning Probe Microscopy of Magnetoelastic Coupling in Galfenol”

Lane Martin, Scott MacLaren
University of Illinois, Urbana-Champaign
“Band Excitation Studies of Losses in Local Switching of Modern Ferroelectric and Multiferroic Thin Films”

Gunter Moeller, George Papakonstantopoulos
Arkema Inc.
“Band Excitation AFM to Develop a Dynamic Mechanical Analysis Method for Polymers”

Brian Rodriguez
University College of Dublin
“Decoupling Elastic and Electromechanical Responses Using Band Excitation Scanning Probe Microscopy”

Neil Thompson, Colin Grant, Nagatha Wijayathunga
University of Leeds
“Band Excitation AFM of Collageneous Materials”

Description

Band Excitation (BE) is a new Scanning Probe Microscopy (SPM) technique that has shown great promise in mapping the conservative interactions, nonlinearities, and energy dissipation of materials on the nanoscale.1 The quality factor, Q, of the cantilever vibrating in the vicinity of the surface is a parameter that is inversely proportional to energy dissipation in the tip-surface junction. However, standard single-frequency SPM experiments are incapable of providing this energy transfer information quantitatively, since only two parameters (e.g. amplitude and phase) are measured experimentally, while at least three are required to describe the dynamics of the system. Frequency sweeps using standard lock-in techniques can be performed to determine Q, but the large time requirements are impractical for imaging. Stephen Jesse and Sergei Kalinin at Oak Ridge National Laboratory and their collaborators, including AFM manufacturer Asylum Research, synthesized an excitation signal programmed with a finite amplitude and phase in a predetermined frequency range to drive the cantilever electrically, magnetically, or acoustically and probe the response at multiple frequencies at once. This method extends to energy dissipation measurements since amplitude and phase response can be determined simultaneously over a range of frequencies, even in low Q-factor environments such as liquids. The BE method is a fast and sensitive technique which may be useful for understanding and mitigating energy losses in magnetic, electrical, and electromechanical processes and technologies.

Contact Information

Please contact Dr. Roger Proksch at Asylum Research for further information and to discuss the Band Excitation Technique.
Email: grants@AsylumResearch.com

Reference

  1. S. Jesse, S. V. Kalinin, R. Proksch et al., "The band excitation method in scanning probe microscopy for rapid mapping of energy dissipation on the nanoscale," Nanotechnology 18 (43) (2007).

 

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Operational principle of the BE method in SPM. The excitation signal is digitally synthesized to have a predefined amplitude and phase in the given frequency window. The cantilever response is detected and Fourier transformed (FFT) at each pixel in an image. The ratio of the fast FFT of response and excitation signals yields the cantilever response (transfer function). Fitting the response to the simple harmonic oscillator yields amplitude, resonance frequency, and Q-factor that are plotted to yield 2D images, or used as feedback signals.1 Reprinted with permission (see reference 1).

 

 

click to enlarge

Excitation (blue) and response (red) signals in standard SPM techniques in (top left) time domain and (top right) Fourier domain. In BE, the system response is probed in the specified frequency range (e.g. encompassing a resonance), as opposed to a single frequency in conventional SPMs. Reprinted with permission. (See reference 1).

 

 


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