Quantifying Electric Field Gradient Fluctuations over Polymers Using Ultrasensitive Cantilevers

Yazdanian, Showkat M.; Hoepker, Nikolas; Kuehn, Seppe; Loring, Roger F.; Marohn, John A.

doi:10.1021/nl9004332

Cited by 32 publications

(66 citation statements)

References 48 publications

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“…3(b)] as a result of 1/f-like frequency fluctuations. 11 Even in the presence of enhanced frequency jitter, however, the mean square thermal amplitude remains in agreement with the equipartition theorem Fig. 3(b)].…”

Section: Surface Dissipationsupporting

confidence: 65%

Silicon Nanowires Feel the Force of Magnetic Resonance

Mamin¹,

Rugar²

2012

Physics

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The authors report the use of a radio frequency (rf) silicon nanowire mechanical oscillator as a low-temperature nuclear magnetic resonance force sensor to detect the statistical polarization of 1 H spins in polystyrene. To couple the 1 H spins to the nanowire oscillator, a magnetic resonance force detection protocol was developed that utilizes a nanoscale current-carrying wire to produce large time-dependent magnetic field gradients as well as the rf magnetic field. Under operating conditions, the nanowire experienced negligible surface-induced dissipation and exhibited an ultralow force noise near the thermal limit of the oscillator.

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Section: Surface Dissipationsupporting

confidence: 65%

Silicon Nanowires Feel the Force of Magnetic Resonance

Mamin¹,

Rugar²

2012

Physics

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“…3(b)) as a result of 1/f-like frequency fluctuations 11 . Even in the presence of enhanced frequency jitter, however, the mean square thermal amplitude remains in agreement with the equipartition theorem The time-dependent force exerted on the SiNW by a single spin is …”

Section: Surface Dissipationmentioning

confidence: 99%

Nanomechanical detection of nuclear magnetic resonance using a silicon nanowire oscillator

et al. 2012

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The authors report the use of a radio frequency silicon nanowire mechanical oscillator as a lowtemperature nuclear magnetic resonance force sensor to detect the statistical polarization of 1 H spins in polystyrene. In order to couple the 1 H spins to the nanowire oscillator, a magnetic resonance force detection protocol was developed which utilizes a nanoscale current-carrying wire to produce large timedependent magnetic field gradients as well as the rf magnetic field. Under operating conditions, the nanowire experienced negligible surface-induced dissipation and exhibited an ultralow force noise near the thermal limit of the oscillator.

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“…It was necessary to increase the tip-sample separation to 400 nm for 24.9 K because the magnitude of the cantilever frequency fluctuations caused by surface noise was significant enough to obscure the measurement. 20 Effects due to surface noise have previously been shown to increase with sample temperature. 21 Also, since the measured frequency change became small at 24.9 K compared to the noise, it was necessary to increase B 1 from 1.06 mT to 1.7 mT to increase the polarization fraction being inverted.…”

mentioning

confidence: 99%

“…The known sources of frequency noise are (1) probe head vibrations which cause tip-sample gap fluctuations, which then induce cantilever frequency jitter at small tip-sample separation, and (2) surface induced cantilever dissipation which increases with increasing sample temperature and decreasing tip-sample separations. 20,23 The first source of noise can be managed with probe head vibration isolation, while the latter has no clear solution for every type of sample. The technique demonstrated here significantly reduces the experimental time required for a spin-lattice inversion-recovery measurement.…”

mentioning

confidence: 99%

Single-shot nuclear magnetization recovery curves with force-gradient detection

Alexson

Hickman

Marohn

et al. 2012

Applied Physics Letters

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We measure the spin-lattice relaxation time as a function of sample temperature in GaAs in a real-time single-shot inversion recovery experiment using spin force gradients acting on a magnetic tipped cantilever. After inverting 69 Ga spins localized near the magnet with a single 20 ms adiabatic rapid passage sweep, the spins' magnetization recovery was passively tracked by recording the cantilever's frequency change, which is proportional to the longitudinal component of the spins' magnetization. The cantilever's frequency was recorded for a time 3*T 1 for sample temperatures ranging from 4.8 to 25 K. The temperature dependence was observed for the Magnetic resonance force microscopy (MRFM) combines the benefits of the two mature fields of magnetic resonance imaging and cantilever based scanning probe microscopy.1 The technology is pressing towards three dimensional imaging at the nanometer scale while providing chemically selective information, where a wide arsenal of nuclear magnetic resonance (NMR) spectroscopic techniques can be used. MRFM is an attractive tool, as it can provide both spatial imaging and chemical characterization on samples such as biological organisms, organic molecules, superconductors, 2,3 and the expanding class of engineered nanomaterials. Mechanically detected NMR has been previously reported on inorganic materials including GaAs, 4,5 CaF, 6 and imaging on an organic specimen. 7A basic measurement in NMR is that of the spin-lattice relaxation time (T 1 ) with an inversion recovery experiment. An understanding of the spin relaxation mechanisms for a sample is essential for interpretation of NMR data and proper identification of a material's structure. Knowledge of T 1 finds use in many areas, i.e., superconductors, 2 semiconductors, 8 and organic materials. 9 Extensive studies have been carried out for the spin 3/2 quadrupolar nuclei in GaAs semiconductors, over wide temperature ranges 10 and doping properties, 11,12 where the relative contributions from quadrupolar mechanisms of relaxation and the roles of acoustic and optical phonons on relaxation rates have been neatly sorted out. The modern inductively detected NMR system is sensitive only to the transverse magnetization. Using inductively detected NMR to determine T 1 requires applying a polarizing magnetic field along the z axis and measuring the precession of magnetization in the xy plane. In solids, the transverse magnetization typically dephases in a time T 2 which is on the order of only 100 microseconds (typically much less than T 1 ). A standard NMR inversion recovery experiment is performed by inverting the magnetization, waiting some fraction of the T 1 time, laying the remaining polarization in the xy plane, and recording its magnitude by measuring the size of the free induction decay (FID). One must then wait a time the order of T 1 for the magnetization to recover before performing the experiment over again. To obtain N points on the T 1 curve takes a time the order of N*T 1 . For samples with a long T 1 , this prese...

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Quantifying Electric Field Gradient Fluctuations over Polymers Using Ultrasensitive Cantilevers

Cited by 32 publications

References 48 publications

Silicon Nanowires Feel the Force of Magnetic Resonance

Silicon Nanowires Feel the Force of Magnetic Resonance

Nanomechanical detection of nuclear magnetic resonance using a silicon nanowire oscillator

Single-shot nuclear magnetization recovery curves with force-gradient detection

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