Date of Award

12-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical and Computer Engineering (Holcomb Dept. of)

Committee Member

Pingshan Wang, Committee Chair

Committee Member

Hai Xiao

Committee Member

Igor Luzinov

Committee Member

Eric G Johnson

Abstract

The dissertation focuses on the development of a novel electron spin resonance (ESR) spectroscopy based on an RF interferometer. The ESR spectroscopy is broadband and quantitative which is tunable over a wide frequency range, in which the RF interferometer is used to remove radio-frequency (RF) probing signals at the detector. With a planar microwave resonator (MR) the ESR spectroscopy is able to measure as low as 0.2 µg (2.8×1014 spins) DPPH (2,2-diphenyl-1-picrylhydrazyl) sample at a signal-to-noise ratio (SNR) of ~ 121 at room temperature. The broadband ESR operation capability is investigated with a broadband meander micro-strip line (MML) by measuring 6 μg (8.4×1015) DPPH between 8 GHz and 13 GHz at a ~194 SNR with 10 kHz VNA IF. The obtained sensitivity is significantly higher than that of current broadband ESR methods. In both MR and MML cases, dispersion and absorption ESR signals at room temperature are simultaneously obtained. With MML structures, the quantification of permeability μ(ω)=μ’ (ω) -jμ”(ω) is possible. The ESR techniques is a promising technique in the examination of magnetic particles and thin films. More work is needed to further improve ESR sensitivity and quantification accuracy.

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