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FEW ELECTRON PARAMAGNETIC RESONANCES DETECTION TECHNIQUES ON THE RUBY SURFACE

Li, Xiying
http://rave.ohiolink.edu/etdc/view?acc_num=case1121296112

Abstract Details

2005, Doctor of Philosophy, Case Western Reserve University, Electrical Engineering.
A method based on the highly localized Evanescent Microware Microscopy (EMM) is developed to spatially resolve small number of Electron Paramagnetic Resonance (EPR), also called Electron Spin Resonance (ESR) transitions on the surface of a signal crystal ruby (Al2O3 doped with Cr3+). The EMM probe operates at a resonate frequency of 3.7 GHz, corresponding to a classical S-band EPR, in a precisely controlled biasing electromagnetic field in the range of 100 to 7000 Gauss. To obtain the highest signal to noise ratio in the overwhelming noise background, a magnetic field modulation with amplitude of 2.0 Gauss and frequency of 5.2 kHz has been applied along with a Lock-in Amplifier, which detects weak signals in very narrow band frequency. Three distinct EPR peaks detected at 1300, 2800 and 5510 Gauss, have demonstrated that three unpaired Cr3+ electrons have four distinct energy levels in the presence of an external magnetic field. Real-time EPR signal measurement software has been developed to control the biasing magnetic fields, collect and display the EPR signals in real time. To observe the weak EPR signal, the measurement speed is set at 400 ms per data point with the time constant of the lock-in amplifier set at 30 ms. The current EMM probe with system overall Q factor of 4,500-5,500, is capable of resolving 20,000 spin transitions with spin-spin relaxation time of around 3 Nano seconds. While the minimum number of detectable spin centers for the commercially available EPR instruments is more than ten million without any spatial information for the spin centers. With more spatially confined EMM probe, the minimum detectable spin transition is expected to reach about 2,000 spin transitions or lower. The ultimate goal of this research is to achieve the minimum detectable spin transition of one single electron using micro-fabricated Atomic Force Microscopy (AFM) EMM probes.
Massood Tabib-Azar (Advisor)
107 p.
Electron Paramagnetic Resonance; Electron Spin Resonance; EPR, ESR; Microwave Frequency

Recommended Citations

Citations

  • Li, X. (2005). FEW ELECTRON PARAMAGNETIC RESONANCES DETECTION TECHNIQUES ON THE RUBY SURFACE [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1121296112

    APA Style (7th edition)

  • Li, Xiying. FEW ELECTRON PARAMAGNETIC RESONANCES DETECTION TECHNIQUES ON THE RUBY SURFACE. 2005. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1121296112.

    MLA Style (8th edition)

  • Li, Xiying. "FEW ELECTRON PARAMAGNETIC RESONANCES DETECTION TECHNIQUES ON THE RUBY SURFACE." Doctoral dissertation, Case Western Reserve University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1121296112

    Chicago Manual of Style (17th edition)

case1121296112
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© 2005, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.
Release 3.2.12