scholarly journals Dynamics of frequency-swept nuclear spin optical pumping in powdered diamond at low magnetic fields

2019 ◽  
Vol 116 (7) ◽  
pp. 2512-2520 ◽  
Author(s):  
Pablo R. Zangara ◽  
Siddharth Dhomkar ◽  
Ashok Ajoy ◽  
Kristina Liu ◽  
Raffi Nazaryan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Optical Pumping ◽  
Spin Dynamics ◽  
Optical Excitation ◽  
Microwave Frequency ◽  
Sweep Rate ◽  
Nitrogen Vacancy ◽  
Diamond Surface

A broad effort is underway to improve the sensitivity of NMR through the use of dynamic nuclear polarization. Nitrogen vacancy (NV) centers in diamond offer an appealing platform because these paramagnetic defects can be optically polarized efficiently at room temperature. However, work thus far has been mainly limited to single crystals, because most polarization transfer protocols are sensitive to misalignment between the NV and magnetic field axes. Here we study the spin dynamics of NV−13C pairs in the simultaneous presence of optical excitation and microwave frequency sweeps at low magnetic fields. We show that a subtle interplay between illumination intensity, frequency sweep rate, and hyperfine coupling strength leads to efficient, sweep-direction-dependent 13C spin polarization over a broad range of orientations of the magnetic field. In particular, our results strongly suggest that finely tuned, moderately coupled nuclear spins are key to the hyperpolarization process, which makes this mechanism distinct from other known dynamic polarization channels. These findings pave the route to applications where powders are intrinsically advantageous, including the hyperpolarization of target fluids in contact with the diamond surface or the use of hyperpolarized particles as contrast agents for in vivo imaging.

SELECTIVE AMPLIFICATION OF NARROW RESONANCE FORMED IN TRANSMISSION SPECTRUM OF Rb NANO-CELL IN MAGNETIC FIELD

2012 ◽  
Vol 15 ◽  
pp. 9-15
Author(s):  
A. SARGSYAN ◽  
G. HAKHUMYAN ◽  
R. MIRZOYAN ◽  
A. PAPOYAN ◽  
D. SARKISYAN ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Transmission Spectrum ◽  
Optical Pumping ◽  
Atomic Transition ◽  
New Method ◽  
Narrow Resonance ◽  
Selective Amplification ◽  
Resonant Transmission

Recently it was shown that "λ-Zeeman Technique" (λ-ZT) is a convenient tool to study individual transitions between the Zeeman sublevels of hyperfine levels in an external magnetic field. λ-ZT is based on resonant transmission spectrum of nanometric thin cell (NTC) of thickness L = λ, where λ is the resonant wavelength 794 nm for Rb D1 line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field. Examination of VSOP resonances allows one to identify and investigate an atomic transition in the range of magnetic fields 10 - 5000 G. Here we present a new method for selective addressing of VSOP resonance amplification (more than 10 times).

scholarly journals Carbon-13 dynamic nuclear polarization in diamond via a microwave-free integrated cross effect

2019 ◽  
Vol 116 (37) ◽  
pp. 18334-18340
Author(s):  
Jacob Henshaw ◽  
Daniela Pagliero ◽  
Pablo R. Zangara ◽  
María B. Franzoni ◽  
Ashok Ajoy ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Dynamic Nuclear Polarization ◽  
Color Center ◽  
Nuclear Polarization ◽  
Optical Excitation ◽  
Zeeman Splitting ◽  
Nitrogen Vacancy ◽  
Field Dynamic ◽  
Diamond Powders ◽  
Promising Source

Color-center–hosting semiconductors are emerging as promising source materials for low-field dynamic nuclear polarization (DNP) at or near room temperature, but hyperfine broadening, susceptibility to magnetic field heterogeneity, and nuclear spin relaxation induced by other paramagnetic defects set practical constraints difficult to circumvent. Here, we explore an alternate route to color-center–assisted DNP using nitrogen-vacancy (NV) centers in diamond coupled to substitutional nitrogen impurities, the so-called P1 centers. Working near the level anticrossing condition—where the P1 Zeeman splitting matches one of the NV spin transitions—we demonstrate efficient microwave-free13C DNP through the use of consecutive magnetic field sweeps and continuous optical excitation. The amplitude and sign of the polarization can be controlled by adjusting the low-to-high and high-to-low magnetic field sweep rates in each cycle so that one is much faster than the other. By comparing the13C DNP response for different crystal orientations, we show that the process is robust to magnetic field/NV misalignment, a feature that makes the present technique suitable to diamond powders and settings where the field is heterogeneous. Applications to shallow NVs could capitalize on the greater physical proximity between surface paramagnetic defects and outer nuclei to efficiently polarize target samples in contact with the diamond crystal.

Magnetism of Bismuth(III) Oxide-Based Compounds

2015 ◽  
Vol 233-234 ◽  
pp. 113-116
Author(s):  
Eleonora A. Kravchenko
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spin Dynamics ◽  
Spin Echo ◽  
Magnetic Moments ◽  
Fold Increase ◽  
Zero Field ◽  
Line Shapes ◽  
Nuclear Magnetic Moments ◽  
Magnetic Splitting

209Bi NQR experiments, including analysis of zero-field line shapes, Zeeman-perturbed patterns and zero-field spin-echo envelopes were made to examine magnetic splitting of resonances revealed in the spectra of Main group element compounds of general composition BakBilAmOn (A=Al, В, Ge, Br, Cl). The results were explained assuming the existence in the compounds of ordered internal magnetic fields from 5 to 250 G which notably exceed those of nuclear magnetic moments. A dramatic (8−10-fold) increase in the resonance intensities, instead of broadening and fading, was observed for such compounds upon applying weak (below 500 Oe) external magnetic fields. The effect was shown to relate to the spin dynamics, namely, to the influence of external magnetic field on the nuclear spin-spin relaxation of the compounds with anomalous magnetic properties. In α-Bi2O3, paramagnetism depending on the thermal prehistory of a sample was found using SQUID-technique; magnetoelectric effect linear in magnetic field was also observed for this oxide.

scholarly journals Magnetic Forces Enable Control of Biological Processes In Vivo

2020 ◽  
pp. 1-21
Author(s):  
Gang Bao
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Viral Vector ◽  
Biological Effects ◽  
Neuron Activity ◽  
Biological Functions ◽  
Magnetic Iron Oxide Nanoparticles ◽  
Magnetic Forces ◽  
Drug Molecules

Abstract Similar to mechanical forces that can induce profound biological effects, magnetic fields can have a broad range of implications to biological systems, from magnetoreception that allows an organism to detect a magnetic field to perceive direction, altitude or location, to the use of heating induced by magnetic field for altering neuron activity. This review focuses on the application of magnetic forces generated by magnetic iron oxide nanoparticles (MIONs), which can also provide imaging contrast and mechanical/thermal energy in response to an external magnetic field, a special feature that distinguishes MIONs from other nanomaterials. The magnetic properties of MIONs offer unique opportunities for enabling new biological functions under different magnetic fields. Here we describe the approaches of utilizing the forces generated by MIONs under applied magnetic field to enable new biological functions, including the targeting of drug molecules to a specific tissue, increasing vessel permeability for improving drug delivery, and activating a particular viral vector for spatial control of genome editing in vivo. The opportunities of using nanomagnets for a broad range of biomedical applications are briefly discussed.

scholarly journals Radical pairs can explain magnetic field and lithium effects on the circadian clock

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Hadi Zadeh-Haghighi ◽  
Christoph Simon
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Circadian Clock ◽  
Spin Dynamics ◽  
Hyperfine Interactions ◽  
Oscillator Model ◽  
Radical Pair Mechanism ◽  
Dependent Manner ◽  
Radical Pairs ◽  
Chemical Oscillator

AbstractDrosophila’s circadian clock can be perturbed by magnetic fields, as well as by lithium administration. Cryptochromes are critical for the circadian clock. Further, the radical pairs in cryptochrome also can explain magnetoreception in animals. Based on a simple radical pair mechanism model of the animal magnetic compass, we show that both magnetic fields and lithium can influence the spin dynamics of the naturally occurring radical pairs and hence modulate the circadian clock’s rhythms. Using a simple chemical oscillator model for the circadian clock, we show that the spin dynamics influence a rate in the chemical oscillator model, which translates into a change in the circadian period. Our model can reproduce the results of two independent experiments, magnetic field and lithium effects on the circadian clock. Our model predicts that stronger magnetic fields would shorten the clock’s period. We also predict that lithium influences the clock in an isotope-dependent manner. Furthermore, our model also predicts that magnetic fields and hyperfine interactions modulate oxidative stress. The findings of this work suggest that the quantum nature of radical pairs might play roles in the brain, as another piece of evidence in addition to recent results on xenon anesthesia and lithium effects on hyperactivity.

scholarly journals Magnetic field-induced enhancement of the nitrogen-vacancy fluorescence quantum yield

Nanoscale ◽  
2017 ◽  
Vol 9 (27) ◽  
pp. 9299-9304 ◽  
Author(s):  
M. Capelli ◽  
P. Reineck ◽  
D. W. M. Lau ◽  
A. Orth ◽  
J. Jeske ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Yield ◽  
Magnetic Fields ◽  
Fluorescence Quantum Yield ◽  
Fluorescence Emission ◽  
Excitation Power ◽  
Nitrogen Vacancy ◽  
High Magnetic Fields

The nitrogen-vacancy (NV) centre in diamond is a remarkable optical defect with broad applications. We demonstrate that its fluorescence emission is enhanced at high magnetic fields with low excitation power.

scholarly journals The Role of Water in the Effect of Weak Combined Magnetic Fields on Production of Reactive Oxygen Species (ROS) by Neutrophils

2020 ◽  
Vol 10 (9) ◽  
pp. 3326
Author(s):  
Vadim V. Novikov ◽  
Elena V. Yablokova ◽  
Evgeny E. Fesenko
Keyword(s):  
Magnetic Field ◽  
Reactive Oxygen Species ◽  
Magnetic Fields ◽  
Reactive Oxygen ◽  
Microwave Frequency ◽  
Ion Cyclotron Resonance ◽  
Ros Production ◽  
Oxygen Species ◽  
Hydronium Ion ◽  
Pre Treatment

Various models have been used to demonstrate the pronounced effects of the microwave frequency range electromagnetic fields, as well as weak and very weak combined collinear magnetic fields (CMF) with static and variable components in the order of micro- and nano-tesla. One of such models, previously shown to be sensitive to variations in the parameters of applied magnetic fields, is the neutrophil respiratory burst. Using luminol-enhanced cell chemiluminescence assay, we studied the effects of the CMF exerted directly on neutrophil suspensions and, indirectly, through aqueous solutions. To experimentally create a uniform standard weak CMF with 60 µT static and 100 nT alternating magnetic field components, we engineered a shielded magnetic field induction device. CMF applied directly to neutrophils enhanced reactive oxygen species (ROS) production by more than 36%. The pronounced stimulating effect was observed only when using the signals that included the frequency of 12.6 Hz that corresponds to the ion cyclotron resonance (ICR) frequency of the hydrated hydronium ion. Similarly, to direct exposure, CMF pre-treatment of a water sample subsequently added to the neutrophil suspension increased ROS production by 66%. The effect of CMF pre-treatment was retained after a series of dilutions and mechanical treatment but disappeared in “magnetic vacuum” or without mechanical influence. Therefore, weak and super weak magnetic fields may indirectly, via water, activate ROS production by neutrophils, provided that modulation of super weak component of collinear field corresponds to the ICR frequency of the hydrated hydronium ion.

scholarly journals Photoinduced spin dynamics in a uniaxial intermetallic heterostructure $$\hbox {TbCo}_2/\hbox {FeCo}$$

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sergei Ovcharenko ◽  
Mikhail Gaponov ◽  
Alexey Klimov ◽  
Nicolas Tiercelin ◽  
Philippe Pernod ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Dynamics ◽  
Thermal Relaxation ◽  
Optical Excitation ◽  
Initial Position ◽  
Light Polarization ◽  
Spin Reorientation ◽  
Maximum Deviation ◽  
Polarization Rotation ◽  
The Time Domain

Abstract Intermetallic heterostructures of rare-earth and transition metals exhibit physical properties prospective for various applications. These structures combine giant magnetostriction, controllable magnetic anisotropy, magneto-optical activity and allow spin reorientation transitions (SRT) induced by magnetic field at room temperature. Here, we present the results of a study of spin dynamics induced by ultrafast optical excitation in the $$\hbox {TbCo}_2\hbox {/FeCo}$$ TbCo 2 /FeCo heterostructure. The time dependence of the light polarization rotation excited by a pump optical pulse with a duration of 35 fs was measured in the total range of the SRT created by external DC magnetic field. We found hysteretic dependence of the polarization rotation on magnetizing field that is specific for spin dynamics near SRT. Enhancement of the rotation is observed in the critical points of the SRT and near the points of magnetization switch from metastable to stable spin states. In the time-domain, two characteristic delays of 20 ps and 200 ps were found, corresponding to the maximum deviation of the light polarization after excitation. The first is explained by the precession motion of spins out of the plane of the structure. The latter is accounted for the spin in-plane deviation from its initial position and thermal relaxation of the anisotropy.

scholarly journals In vivo magnetic recording of neuronal activity

2016 ◽  
Author(s):  
Laure Caruso ◽  
Thomas Wunderle ◽  
Christopher Murphy Lewis ◽  
Joao Valadeiro ◽  
Vincent Trauchessec ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Visual Cortex ◽  
Magnetic Fields ◽  
Neuronal Activity ◽  
Field Measurements ◽  
Magnetic Sensors ◽  
List Type ◽  
Spin Electronics ◽  
Magnetic Field Measurements

SUMMARYNeuronal activity generates ionic flows and thereby both magnetic fields and electric potential differences, i.e. voltages. Voltage measurements are widely used, but suffer from isolating and smearing properties of tissue between source and sensor, are blind to ionic flow direction, and reflect the difference between two electrodes, complicating interpretation. Magnetic field measurements could overcome these limitations, but have been essentially limited to magnetoencephalography (MEG), using centimeter-sized, helium-cooled extracranial sensors. Here, we report on in vivo magnetic recordings of neuronal activity from visual cortex of cats with magnetrodes, specially developed needle-shaped probes carrying micron-sized, non-cooled magnetic sensors based on spin electronics. Event-related magnetic fields inside the neuropil were on the order of several nanoteslas, informing MEG source models and efforts for magnetic field measurements through MRI. Though the signal-to-noise ratio is still inferior to electrophysiology, this proof of concept demonstrates the potential to exploit the fundamental advantages of magnetophysiology.HIGHLIGHTSSpin-electronics based probes achieve local magnetic recordings inside the neuropilMagnetic field recordings were performed in vivo, in anesthetized cat visual cortexEvent-related fields (ERFs) to visual stimuli were up to several nanoteslas in sizeERFs could be detected after averaging less than 20 trialsIN BRIEFCaruso et al. report in vivo, intra-cortical recordings of magnetic fields that reflect neuronal activity, using magnetrodes, i.e. micron size magnetic sensors based on spin electronics.

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