Nanoscale magnetic resonance imaging using silicon nanowire oscillators

Nichol, John

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https://hdl.handle.net/2142/46621 Copy

Description

Title

Nanoscale magnetic resonance imaging using silicon nanowire oscillators

Author(s)

Nichol, John

Issue Date

2014-01-16T17:56:29Z

Director of Research (if dissertation) or Advisor (if thesis)

Budakian, Raffi

Doctoral Committee Chair(s)

Cooper, S. Lance

Committee Member(s)

• Budakian, Raffi
• DeMarco, Brian L.
• Stone, Michael

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• magnetic resonance imaging
• silicon nanowire
• scanning probe microscopy

Abstract

This dissertation describes new techniques for nanometer-scale magnetic resonance imaging. We report methods that enable the use of (1) silicon nanowires as ultrasensitive force transducers for magnetic resonance detection and (2) pulsed magnetic resonance techniques for nanometer-scale imaging and spectroscopy. Because of their small size and high aspect ratio, silicon nanowires have inherently low mechanical dissipation and correspondingly low thermal force noise. We have developed a method for displacement detection of silicon nanowire oscillators using a polarized fiber-optic interferometer. Even though the nanowires have widths much smaller than optical wavelengths, interferometry enables sensitive displacement detection because the nanowires exhibit enhanced optical scattering when the incident polarization is parallel to the nanowire axis. Interferometry also allows us to implement active feedback control of nanowire oscillators. To perform magnetic resonance detection using the nanowires, we have developed a technique, which uses electric currents through a nanoscale metal constriction to generate time-dependent magnetic field gradients to couple nuclear spins in a sample to the resonant displacement of the nanowire oscillator. The ability to generate time-dependent fields and gradients together with a new spin noise encoding protocol enable us to use pulsed magnetic resonance techniques for nanometer-scale samples. We demonstrate Fourier transform magnetic resonance imaging and spectroscopy of a statistically polarized polystyrene sample with roughly 10-nm spatial resolution.

Graduation Semester

2013-12

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http://hdl.handle.net/2142/46621

Copyright and License Information

Copyright 2013 John M. Nichol

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