ESTIMATION OF BROAD QUADRUPOLE RESONANCE LINESHAPES USING MEASUREMENTS OBTAINED WITH NARROWBAND PROBES

Open Access
- Author:
- Schmitt, Drew
- Area of Honors:
- Electrical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Jeffrey Louis Schiano, Thesis Supervisor
Jeffrey Louis Schiano, Thesis Supervisor
John Douglas Mitchell, Thesis Honors Advisor - Keywords:
- quadrupole resonance
QR
reconstruction
probes - Abstract:
- The specific aim of this study is to test the following hypothesis. Using a pulsed quadrupole resonance spectrometer, it is possible to reconstruct the spectrum of a quadrupole resonance signal whose bandwidth is significantly larger than that of the spectrometer. The proposed approach is to combine spectrometer measurements taken at several distinct operating frequencies that span the bandwidth of the quadrupole resonance signal. This hypothesis will be evaluated in three steps. The first step is to provide a theoretical justification for a series of three different reconstruction algorithms. The second step is to test the reconstruction algorithms using computer simulations. The third and final step is to evaluate the reconstruction algorithms using experimental measurements. The numerical simulations were used to simulate the effect of measuring a wideband signal with a comparatively narrowband spectrometer. The effects of thermal noise were incorporated into the computational model so that the simulations would closely mimic physical experiments. The experimental tests conducted in the laboratory on organic compounds test the efficacy of the proposed technique. In the end, this study analyzes the advantages achieved by using a narrowband spectrometer to sample and estimate a broad quadrupole resonance signal. Two of the three reconstruction algorithms were adversely affected by the short observation windows used to observe quadrupole resonance responses. The third algorithm was not similarly affected and yielded a reconstructed spectra that closely matched the lineshape of the quadrupole resonance signal, both in simulations and experiment.