Low-Frequency NMR and NQR with a dc SQUID Amplifier [Thesis]

Thesis/Dissertation · Thu Nov 01 04:00:00 EST 1990

OSTI ID:5775965

Fan, Nong-Qiang ^[1]

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1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

A sensitive Fourier-transform spectrometer based on a dc SQUID (Superconducting QUantum Interference Device) has been developed for the direct detection of nuclear magnetic resonance (NMR) in zero applied magnetic field and pure nuclear quadrupole resonance (NQR) at low frequencies. The motivation to detect zero field NMR and NQR is to provide a new high resolution spectroscopy technique at frequencies below 200 kHz to study ultra-weak interactions in chemicals and materials. By comparing the sensitivity of a SQUID amplifier with that of a conventional semiconductor amplifier, it is shown that a SQUID amplifier is essential for the direct detection of low frequency resonant signals. The spectrometer has a frequency response extending from about 10 to 200 kHz, and a recovery time (after the magnetic pulse is removed) of about 50 μs. The spectrometer is used to detect NMR spectra from Pt and Cu metal powders in a magnetic field of 6 mtesla, and NQR spectra from ²D in a tunneling methyl group and ¹⁴N in NH₄CIO₄. Finally, the zero field NMR spectrum from a quantum tunneling methyl group is calculated.

• Research Organization: Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Energy Research (ER)
• Contributing Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5775965
• Report Number(s): LBL--30096; ON: DE91011829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
400101* -- Activation
Nuclear Reaction
Radiometric & Radiochemical Procedures
426001 -- Engineering-- Superconducting Devices & Circuits-- (1990-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKYL RADICALS
AMMONIUM COMPOUNDS
COPPER
ELECTRONIC EQUIPMENT
ELEMENTS
EQUIPMENT
FLUXMETERS
FOURIER TRANSFORM SPECTROMETERS
ISOTOPES
LIGHT NUCLEI
MAGNETIC FIELDS
MAGNETIC RESONANCE
MEASURING INSTRUMENTS
METALS
METHYL RADICALS
MICROWAVE EQUIPMENT
NITROGEN 14
NITROGEN ISOTOPES
NUCLEAR MAGNETIC RESONANCE
NUCLEAR QUADRUPOLE RESONANCE
NUCLEI
ODD-ODD NUCLEI
PLATINUM
PLATINUM METALS
POWDERS
RADICALS
RESONANCE
SPECTROMETERS
SQUID DEVICES
STABLE ISOTOPES
SUPERCONDUCTING DEVICES
TRANSITION ELEMENTS
TUNNEL EFFECT
ZERO SOUND