Direct current superconducting quantum interference device spectrometer for pulsed nuclear magnetic resonance and nuclear quadrupole resonance at frequencies up to 5 MHz
作者:
Dinh M. TonThat,
John Clarke,
期刊:
Review of Scientific Instruments
(AIP Available online 1996)
卷期:
Volume 67,
issue 8
页码: 2890-2893
ISSN:0034-6748
年代: 1996
DOI:10.1063/1.1147122
出版商: AIP
数据来源: AIP
摘要:
A spectrometer based on a dc superconducting quantum interference device (SQUID) has been developed for the direct detection of nuclear magnetic resonance (NMR) or nuclear quadrupole resonance (NQR) at frequencies up to 5 MHz. The sample is coupled to the input coil of the niobium‐based SQUID via a nonresonant superconducting circuit. The flux locked loop involves the direct offset integration technique with additional positive feedback in which the output of the SQUID is coupled directly to a low‐noise preamplifier. Precession of the nuclear quadrupole spins is induced by a magnetic field pulse with the feedback circuit disabled; subsequently, flux locked operation is restored and the SQUID amplifies the signal produced by the nuclear free induction signal. The spectrometer has been used to detect27Al NQR signals in ruby (Al2O3[Cr3+]) at 359 and 714 kHz. ©1996 American Institute of Physics.
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