We describe the construction of a fast field cycling device capable of sweeping a 4-order-of-magnitude range of magnetic fields, from ∼1 mT to 7 T, in under 700 ms, and which is further extendable to a 1 nT-7 T range. Central to this system is a high-speed sample shuttling mechanism between a superconducting magnet and a magnetic shield, with the capability to access arbitrary fields in between with high resolution. Our instrument serves as a versatile platform to harness the inherent dichotomy of spin dynamics on offer at low and high fields—in particular, the low anisotropy, fast spin manipulation, and rapid entanglement growth at low field as well as the long spin lifetimes, spin specific control, and efficient inductive measurement possible at high fields. Exploiting these complementary capabilities in a single device opens up applications in a host of problems in quantum control, sensing, and information storage, besides in nuclear hyperpolarization, relaxometry, and imaging. In particular, in this paper, we focus on the ability of the device to enable low-field hyperpolarization of 13C nuclei in diamond via optically pumped electronic spins associated with nitrogen vacancy defect centers.
Hyperpolarization is one of the approaches to enhance Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) signal by increasing the population difference between the nuclear spin states. Imaging hyperpolarized solids opens up extensive possibilities, yet is challenging to perform. The highly populated state is normally not replenishable to the initial polarization level by spin-lattice relaxation, which regular MRI sequences rely on. This makes it necessary to carefully “budget” the polarization to optimize the image quality. In this paper, we present a theoretical framework to address such challenge under the assumption of either variable flip angles or a constant flip angle. In addition, we analyze the gradient arrangement to perform fast imaging to overcome intrinsic short decoherence in solids. Hyperpolarized diamonds imaging is demonstrated as a prototypical platform to test the theory.
Carbon capture and sequestration reduces carbon dioxide emissions and is critical in accomplishing carbon neutrality targets. Here, we demonstrate new sustainable, solid-state, polyamine-appended, cyanuric acid–stabilized melamine nanoporous networks (MNNs) via dynamic combinatorial chemistry (DCC) at the kilogram scale toward effective and high-capacity carbon dioxide capture. Polyamine-appended MNNs reaction mechanisms with carbon dioxide were elucidated with double-level DCC where two-dimensional heteronuclear chemical shift correlation nuclear magnetic resonance spectroscopy was performed to demonstrate the interatomic interactions. We distinguished ammonium carbamate pairs and a mix of ammonium carbamate and carbamic acid during carbon dioxide chemisorption. The coordination of polyamine and cyanuric acid modification endows MNNs with high adsorption capacity (1.82 millimoles per gram at 1 bar), fast adsorption time (less than 1 minute), low price, and extraordinary stability to cycling by flue gas. This work creates a general industrialization method toward carbon dioxide capture via DCC atomic-level design strategies.
Understanding the origins of spin lifetimes in hybrid quantum systems is a matter of current importance in several areas of quantum information and sensing. Methods that spectrally map spin relaxation processes provide insight into their origin and can motivate methods to mitigate them. In this paper, using a combination of hyperpolarization and precision field cycling over a wide range (1mT-7T), we map frequency dependent relaxation in a prototypical hybrid system of 13C nuclear spins in diamond coupled to Nitrogen Vacancy centers. Nuclear hyperpolarization through the optically pumped NV electrons allows signal time savings for the measurements exceeding million-fold over conventional methods. We observe that 13C lifetimes show a dramatic field dependence, growing rapidly with field up to 100mT and saturating thereafter. Through a systematic study with increasing substitutional electron (P1 center) concentration as well as 13C enrichment levels, we identify the operational relaxation channels for the nuclei in different field regimes. In particular, we demonstrate the dominant role played by the 13C nuclei coupling to the interacting P1 electronic spin bath. These results pave the way for quantum control techniques for dissipation engineering to boost spin lifetimes in diamond, with applications ranging from engineered quantum memories to hyperpolarized 13C imaging.
Methods of optical dynamic nuclear polarization (DNP) open the door to the replenishable hyperpolarization of nuclear spins, boosting their NMR/MRI signature by orders of magnitude. Nanodiamond powder rich in negatively charged Nitrogen Vacancy (NV) defect centers has recently emerged as one such promising platform, wherein 13C nuclei can be hyperpolarized through the optically pumped defects completely at room temperature and at low magnetic fields. Given the compelling possibility of relaying this 13C polarization to nuclei in external liquids, there is an urgent need for the engineered production of highly hyperpolarizable diamond particles. In this paper, we report on a systematic study of various material dimensions affecting optical 13C hyperpolarization in diamond particles -- especially electron irradiation and annealing conditions that drive NV center formation. We discover surprisingly that diamond annealing at elevated temperatures close to 1720C have remarkable effects on the hyperpolarization levels, enhancing them by upto 36-fold over materials annealed through conventional means. We unravel the intriguing material origins of these gains, and demonstrate they arise from a simultaneous improvement in NV electron relaxation time and coherence time, as well as the reduction of paramagnetic content, and an increase in 13C relaxation lifetimes. Overall this points to significant recovery of the diamond lattice from radiation damage as a result of the high-temperature annealing. Our work suggests methods for the guided materials production of fluorescent, 13C hyperpolarized, nanodiamonds and pathways for their use as multi-modal (optical and MRI) imaging and hyperpolarization agents.
Abstract C 42 H 42 N 2 O 4 , triclinic, P1‾ $P\overline{1}$ (no. 2), a = 9.309(3) Å, b = 14.191(5) Å, c = 14.918(5) Å, α = 69.221(4)°, β = 82.384(5)°, γ = 72.805(4)°, V = 1759.3(10) Å 3 , Z = 2, R gt ( F ) = 0.0699, wR ref ( F 2 ) = 0.1806, T = 296 K.
Significance We report on progress toward combining magnetic resonance imaging (MRI) and optical imaging in diamond microparticles. Our approach relies on the nitrogen vacancy (NV) center-driven optical nuclear hyperpolarizability in diamond particles, that renders them “bright” in MRI while simultaneously fluorescing optically. Both imaging modes allow suppression of background signals. We elucidate how such “dual-mode” imaging can perform better than either modes taken separately, leveraging relative strengths of optics and MRI with respect to resolution and imaging in scattering media. Finally, we propose a protocol for accelerated imaging that exploits the Fourier conjugacy in images obtained via optics and MRI. Our work suggests methods to combine optical and RF imaging in classes of deployable nanoparticles.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)