Polarization enhancement technique for nuclear quadrupole resonance detection

Kim, Y.J.; Karaulanov, T.; Matlashov, Andrei; Newman, Shaun; Urbaitis, Algis V.; Volegov, P. L.; Yoder, Jacob; Espy, Michelle A.

doi:10.1016/j.ssnmr.2014.05.002

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…With the sample flush to the detector, the polarization enhancement factor is greater than 23. This is less than the theoretical maximum 11 and is due to the time spent moving the sample the 4 m from the magnet to the AM. The enhancement factor is still nearly 10 at 5 cm.…”

Section: Resultsmentioning

confidence: 72%

“…4,7,8 In addition, polarization enhancement (PE) techniques 9,10 have also been demonstrated to dramatically improve the NQR signal for certain samples by factors of 10 or greater. 11 With PE combined with sub-femtoTesla sensitive vapor cell atomic magnetometers (AM) for detection, such a system has the potential to improve signal detection in NQR, while also being immune from the electronic noise sources that can plague inductive coil measurements.…”

Section: Introductionmentioning

confidence: 99%

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Polarization enhanced Nuclear Quadrupole Resonance with an atomic magnetometer

Malone

Barrall

Espy

et al. 2016

Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XXI

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Nuclear Quadrupole Resonance (NQR) has been demonstrated for the detection of 14-N in explosive compounds. Application of a material specific radio-frequency (RF) pulse excites a response typically detected with a wirewound antenna. NQR is non-contact and material specific, however fields produced by NQR are typically very weak, making demonstration of practical utility challenging. For certain materials, the NQR signal can be increased by transferring polarization from hydrogen nuclei to nitrogen nuclei using external magnetic fields. This polarization enhancement (PE) can enhance the NQR signal by an order of magnitude or more. Atomic magnetometers (AM) have been shown to improve detection sensitivity beyond a conventional antenna by a similar amount. AM sensors are immune to piezo-electric effects that hamper conventional NQR, and can be combined to form a gradiometer for effective RF noise cancellation. In principle, combining polarization enhancement with atomic magnetometer detection should yield improvement in signal-to-noise ratio that is the product of the two methods, 100-fold or more over conventional NQR. However both methods are even more exotic than traditional NQR, and have never been combined due to challenges in operating a large magnetic field and ultra-sensitive magnetic field sensor in proximity. Here we present NQR with and without PE with an atomic magnetometer, demonstrating signal enhancement greater than 20-fold for ammonium nitrate. We also demonstrate PE for PETN using a traditional coil for detection with an enhancement factor of 10. Experimental methods and future applications are discussed.

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Section: Resultsmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Polarization enhanced Nuclear Quadrupole Resonance with an atomic magnetometer

Malone

Barrall

Espy

et al. 2016

Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XXI

View full text Add to dashboard Cite

show abstract

“…NQR spectroscopy is a solid-state analysis technique that provides a unique chemical fingerprint based on the coupling of nuclear quadrupole moments to their local electric field gradients (27,28). NQR spectroscopy is used to identify powder substances in ambient conditions for security (29)(30)(31) and pharmaceutical (32)(33)(34) applications and to study the temperature-dependent properties of single-crystal materials (35)(36)(37)(38)(39). These applications typically require the ability to detect kilohertz to megahertz frequencies, at low-bias magnetic fields ≲1 mT, with femtotesla sensitivity (40).…”

Section: Introductionmentioning

confidence: 99%

Nuclear quadrupole resonance spectroscopy with a femtotesla diamond magnetometer

et al. 2023

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Radio frequency (RF) magnetometers based on nitrogen vacancy centers in diamond are predicted to offer femtotesla sensitivity, but previous experiments were limited to the picotesla level. We demonstrate a femtotesla RF magnetometer using a diamond membrane inserted between ferrite flux concentrators. The device provides ~300-fold amplitude enhancement for RF magnetic fields from 70 kHz to 3.6 MHz, and the sensitivity reaches ~70 fT√s at 0.35 MHz. The sensor detected the 3.6-MHz nuclear quadrupole resonance (NQR) of room-temperature sodium nitrite powder. The sensor’s recovery time after an RF pulse is ~35 μs, limited by the excitation coil’s ring-down time. The sodium-nitrite NQR frequency shifts with temperature as −1.00±0.02 kHz/K, the magnetization dephasing time is T 2 *=887±51 μs, and multipulse sequences extend the signal lifetime to 332±23 ms, all consistent with coil-based studies. Our results expand the sensitivity frontier of diamond magnetometers to the femtotesla range, with potential applications in security, medical imaging, and materials science.

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Parallel high-frequency magnetic sensing with an array of flux transformers and multi-channel optically pumped magnetometer for hand MRI application

Kim

Savukov

2020

Journal of Applied Physics

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We investigate an approach for parallel high-frequency magnetic sensing based on a multi-channel radio frequency (RF) optically pumped magnetometer (OPM) coupled to multiple flux transformers (FTs) with a focus on hand magnetic resonance imaging (MRI) application at ultra-low field (ULF). Multiple RF OPM sensing channels are realized by using a single large-area alkali-metal vapor cell and two laser beams for pumping and probing, shared for all the channels. This design leads to significant cost reduction when multi-channel sensing is desirable, as in the case of ULF MRI. The FT, composed of two connected coils, serves as a transmitter of a target magnetic field to the OPM, while decoupling the OPM from untargeted magnetic fields in the sensing area that can limit the OPM performance. For hand MRI application, theoretical and numerical analysis is performed to determine an optimal geometry for the FT array that could improve signal-to-noise ratio (SNR) and sufficiently reduce crosstalk between FTs. We estimate that the optimized multi-channel FT-OPM sensor can achieve a magnetic field sensitivity of the order of 1fT/Hz1/2 above 100 kHz, which would be sufficient for 1 mm resolution MRI. In general, the multi-channel capability enables simultaneous magnetic measurements, thus reducing the sensing time and improving the SNR, and we anticipate many applications of the multi-channel FT-OPM sensor beyond the targeted here hand MRI: anatomical parallel ULF MRI of the human brain and other parts of the body, airport security screening, magnetic material imaging, and many others.

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Polarization enhancement technique for nuclear quadrupole resonance detection

Cited by 5 publications

References 24 publications

Polarization enhanced Nuclear Quadrupole Resonance with an atomic magnetometer

Polarization enhanced Nuclear Quadrupole Resonance with an atomic magnetometer

Nuclear quadrupole resonance spectroscopy with a femtotesla diamond magnetometer

Parallel high-frequency magnetic sensing with an array of flux transformers and multi-channel optically pumped magnetometer for hand MRI application

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