Nitrogen In Diamond Research Articles

Laser-polarization-dependent spontaneous emission of the zero phonon line from single nitrogen–vacancy center in diamond

We investigate spontaneous emission properties and control of the zero phonon line (ZPL) from a diamond nitrogen–vacancy (NV) center coherently driven by a single elliptically polarized control field. We use the Schrödinger equation to calculate the probability amplitudes of the wave function of the coupled system and derive analytical expressions of the spontaneous emission spectra. The numerical results show that a few interesting phenomena such as enhancement, narrowing, suppression, and quenching of the ZPL spontaneous emission can be realized by modulating the polarization-dependent phase, the Zeeman shift, and the intensity of the control field in our system. In the dressed-state picture of the control field, we find that multiple spontaneously generated coherence arises due to three close-lying states decaying to the same state. These results are useful in real experiments.

Diamonds in the Attawapiskat area of the Superior craton (Canada): evidence for a major diamond-forming event younger than 1.1 Ga

Here, we compare nitrogen aggregation characteristics and carbon isotopic compositions in diamonds from Mesoproterozoic (T1) and Jurassic (U2) kimberlites in the Attawapiskat area—the first diamond-producing area on the Superior craton. The T1 kimberlite sampled diamonds from the lithospheric mantle at 1.1 Ga, at the same time as the major Midcontinent Rift event. These diamonds have a narrow range in δ13C (mode of −3.4 ‰), with compositions that overlap other diamond localities on the Superior craton. Some diamond destruction must have occurred during the Mesoproterozoic in response to the thermal impact of the Midcontinent Rift—the associated elevated geotherm caused a narrow diamond window (<30 km) close to the base of the lithosphere, compared to a wide diamond window of ~85 km following thermal relaxation (sampled by Jurassic kimberlites, such as U2). T1 diamonds have highly aggregated nitrogen, possibly due to the thermal effect of the rift. Diamond-favourable conditions were re-established in the lithospheric mantle after the thermal impact of the Midcontinent Rift dissipated. The poorly aggregated nature of nitrogen in U2 diamonds—compared to highly aggregated nitrogen in diamonds from T1—indicates that renewed diamond formation must have occurred only after the thermal impact of the Midcontinent Rift at 1.1 Ga had subsided and that these newly formed diamonds were subsequently sampled by Jurassic kimberlites. The overall δ13C distribution for U2 diamonds is distinct to T1 and other Superior diamonds, further suggesting that U2 diamonds are not related to the older pre-rift diamonds.

Characterization of typical infrared characteristic peaks of hydrogen in nitrogen and hydrogen co-doped diamond crystals

The 3107 cm-1 peak is observed in the infrared absorption spectra of all types of Ia diamonds, but it has not been observed in the iron-based catalyst. A series of nitrogen and hydrogen-doped diamond crystals is successfully synthesized using P3N5 as the nitrogen source in a catalyst-carbon system at a lower pressure and temperature (6.3 GPa, 1500 ℃). Fourier transform infrared micro-spectroscopy reveals that the hydrogen atoms existing in the synthesized diamond are in two forms. The one is attributed to the CH bond stretching (3107 cm-1) and bending (1405 cm-1) vibrations of the vinylidene group (C＝CH2). The other is due to sp3 hybridization CH bond symmetric (2850 cm-1) and anti-symmetric (2920 cm-1) vibrations. According to our result, we find that the 3107 cm-1 hydrogen absorption peak is related to the aggregated nitrogen in synthetic diamond. The 3107 cm-1 peak could not be observed in synthetic diamond without aggregated nitrogen, even if it has a high nitrogen concentration. And the hydrogen absorption peaks at 2920 and 2850 cm-1 are more widespread than the absorption peak at 3107 cm-1, this suggests that the sp3 CH bond more widely exists in diamond than the vinylidene group (C＝CH2). Infrared spectra analysis indicates that the hydrogen impurity mainly exists in the natural diamond as vinylidene group as seen from the absorption peak intensity. We believe that our results provide a new way to study the formation mechanism of the natural diamond. Moreover, the ideal synthesis condition in our system supplies a possible way for us to design n-type diamond semiconductor.

Creation of quantum entanglement with two separate diamond nitrogen vacancy centers coupled to a photonic molecule

We explore the entanglement generation and the corresponding dynamics between two separate nitrogen-vacancy (NV) centers in diamond nanocrystal coupled to a photonic molecule consisting of a pair of coupled photonic crystal (PC) cavities. By calculating the entanglement concurrence with readily available experimental parameters, it is found that the entanglement degree strongly depends on the cavity-cavity hopping strength and the NV-center-cavity detuning. High concurrence peak and long-lived entanglement plateau can be achieved by properly adjusting practical system parameters. Meanwhile, we also discuss the influence of the coupling strength between the NV centers and the cavity modes on the behavior of the concurrence. Such a PC-NV system can be employed for quantum entanglement generation and represents a building block for an integrated nanophotonic network in a solid-state cavity quantum electrodynamics platform. In addition, the present theory can also be applied to other similar systems, such as two single quantum emitters positioned close to a microtoroidal resonator with the whispering-gallery-mode fields propagating inside the resonator.

Constraining the internal variability of the stable isotopes of carbon and nitrogen within mantle diamonds

The carbon and nitrogen isotope values of mantle xenoliths and xenocrysts are used to trace the cycling of volatiles in the deep Earth, for example, to place empirical constraints on the origin of diamond-forming carbon in the mantle. The global database for diamond shows that the δ13C value of peridotitic diamonds is very narrow, typically around −5‰, whereas eclogitic diamonds can show positive and very negative δ13C values resembling crustal carbonates and crustal organic carbon (<−40 to >+2‰); commonly interpreted to reflect a relationship between eclogitic diamond formation and subduction zone planet tectonics. Curiously, diamonds from both parageneses can show positive (crust-like) and negative (mantle-like) δ15N values (from <−40 to >+20‰). Most of these data are derived from single stage combustion gas sourced mass spectrometry, which produces simplistic datasets. By fragmenting single diamonds or using in-situ ion-beam techniques it is known that single diamonds can show large-scale heterogeneity for their carbon isotope values and nitrogen abundances, sometimes as large as entire populations of diamond across a few hundred micrometres. What is less well known is the scale of nitrogen isotope heterogeneity within single diamonds, and if the nitrogen isotope heterogeneity of single diamonds can provide an insight into why diamonds that show very restricted δ13C values show a much large range of δ15N values.To investigate the scale, and to determine the origin of the nitrogen isotope heterogeneity (source vs. fractionation during diamond-formation) shown for populations of mantle diamonds we have determined multiple δ13C–δ15N values and nitrogen abundances from 14 monocrystalline (MCDs) and 25 polycrystalline diamonds (PCDs) using step-wise oxidation gas sourced mass spectrometry. These data show that the heterogeneity shown for carbon and nitrogen isotope values from single diamond samples presented here is typically <5‰ and <8‰ respectively, both of which are comparable to the standard deviation for the mean mantle δ13C and δ15N values (±3 and ±4‰). However, there are samples that show much larger heterogeneities for δ13C and δ15N values (≤23‰ and ≤33‰ respectively), which cannot be generated by equilibrium stable isotope fractionation during, or prior to diamond-formation. These data suggest that isotopic heterogeneity may be present within the diamond-forming fluid on sub-mm scale, or that these diamonds formed during multiple diamond-formation events from isotopically distinct sources. From these 39 samples there are only 5 PCDs that show a larger range of carbon isotopes relative to nitrogen isotopes, but of these 5 samples only 2 show a range of δ13C values outside of analytical uncertainty. The remaining 34 samples show a greater isotopic heterogeneity for δ15N relative to δ13C values. The samples with the largest carbon and nitrogen isotopic heterogeneity are also the samples with low-bulk δ13C values (<−10‰), whilst there is no relationship between the ranges of nitrogen isotope values for a given sample and the corresponding bulk δ15N value or nitrogen content.These data show that δ15N values recorded in mantle diamonds are relatively heterogeneous, and can show both mantle-like (negative) and crustal (sedimentary)-like (positive) δ15N values within the same sample. We conclude that the large range of nitrogen isotope values seen within individual diamonds means that the observation of negative, mantle-like, nitrogen in mantle diamonds acquired by single-stage bulk combustion isotope ratio mass spectrometry cannot be used as a conclusive indicator for a mantle origin for the entirety of the diamond-forming carbon, and vice versa. Also, the behaviour of 15N/14N is not coupled with the behaviour of 14N/12C during diamond-formation. Instead, it appears that diamond-forming fluids can have positive and negative δ15N values, irrespective of their δ13C value(s). These data suggest that subduction induced nitrogen isotope heterogeneity may not be coupled with subduction induced carbon isotope heterogeneity in diamond-forming fluids.

Anticorrelation between low δ13C of eclogitic diamonds and high δ18O of their coesite and garnet inclusions requires a subduction origin

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Frontiers in diffraction unlimited optical methods for spin manipulation, magnetic field sensing and imaging using diamond nitrogen vacancy defects

AbstractThe nitrogen vacancy defect centre in diamond has attracted intense research interest owing to their appealing optical and electronic properties, which have laid the ground for new approaches for diffraction unlimited optical methods. In particular, the optical detected magnetic resonance of the electron spin of nitrogen vacancy centre at room temperature underpins many areas in nanophotonics, spintronics and quantum optics. This article reviews the recent development of super-resolution imaging and sensing nanoscopy based on this fascinating defect centre in diamond. These breakthroughs are presently indicating a new class of nanoscale sensors of tiny magnetic and electric fields at room temperature, as well as emerging fluorescent and magnetic probes for next generation nanoscopy and all-optical spin recording.

Evidence for deep mantle convection and primordial heterogeneity from nitrogen and carbon stable isotopes in diamond

Diamond, as the deepest sample available for study, provides a unique opportunity to sample and examine parts of the Earth’s mantle not directly accessible. In order to provide further constraints on mantle convection and deep volatile cycles, we analysed nitrogen and carbon isotopes and nitrogen abundances in 133 diamonds from Juina (Brazil) and Kankan (Guinea). Host syngenetic inclusions within these diamonds indicate origins from the lithosphere, the asthenosphere-transition zone and the lower mantle.Juina and Kankan diamonds both display overall carbon isotopic compositions within the current upper mantle range but the δ13C signatures of diamonds from the asthenosphere-transition zone extend toward very negative and positive values, respectively. Two Kankan diamonds with both lower mantle and asthenosphere-transition zone inclusions (KK-45 and KK-83) are zoned in δ13C, and have signatures consistent with multiple growth steps likely within both the lower mantle and the asthenosphere-transition zone illustrating the transfer of material through the 670km seismic discontinuity.At a given locality, diamonds from the upper and the lower mantle show similar δ15N distributions with coinciding modes within the range defined by typical upper mantle samples, as one might expect for a well stirred reservoir resulting from whole mantle convection.Kankan diamonds KK-11 (lower mantle), KK-21 and KK-92 (both lithospheric) display the lowest δ15N values (-24.9%, -39.4% and -30.4%) ever measured in terrestrial samples, which we interpret as reflecting primordial heterogeneity preserved in an imperfectly mixed convective mantle.Our diamond data thus provide support for deeply rooted convection cells, together with the preservation of primordial volatiles in an imperfectly mixed convecting mantle, thereby reconciling the conflicting interpretations regarding mantle homogeneity derived from geochemical and geophysical studies.

Coupling of ultrathin tapered fibers with high-Q microsphere resonators at cryogenic temperatures and observation of phase-shift transition from undercoupling to overcoupling

We cooled ultrathin tapered fibers to cryogenic temperatures and controllably coupled them with high-Q microsphere resonators at a wavelength close to the optical transition of diamond nitrogen vacancy centers. The 310-nm-diameter tapered fibers were stably nanopositioned close to the microspheres with a positioning stability of approximately 10 nm over a temperature range of 7-28 K. A cavity-induced phase shift was observed in this temperature range, demonstrating a discrete transition from undercoupling to overcoupling.

On the diffusion of NV defects in diamond

AbstractBesides their importance for quantum information processing, NV defects are crucial agents for the diffusion and aggregation of nitrogen in diamond. In the absence of transition metals, it is thought that the first stage of nitrogen aggregation, where close neighbour nitrogen pairs are formed, is mediated by NV defects. Here we use density functional theory to explore the barriers to NV diffusion. We conclude that the barrier is around 5 eV when there is a ready source of vacancies and that this barrier is weakly dependent on pressure.

Synthesis and characterization of p-type boron-doped IIb diamond large single crystals

High-quality p-type boron-doped IIb diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond.

Phase shift spectra of a fiber–microsphere system at the single photon level

We succeeded in measuring phase shift spectra of a microsphere cavity coupled with a tapered fiber using a weak coherent probe light at the single photon level. We utilized a tapered fiber with almost no depolarization and constructed a very stable phase shift measurement scheme based on polarization analysis using photon counting. Using a very weak probe light (n = 0.41), we succeeded in observing the transition in the phase shift spectrum between undercoupling and overcoupling (at gap distances of 500 and 100 nm, respectively). We also used quantum state tomography to obtain a 'purity spectrum'. Even in the overcoupling regime, the average purity was 0.982 ± 0.024 (minimum purity: 0.892), suggesting that the coherence of the fiber-microsphere system was well preserved. Based on these results, we believe this system is applicable to quantum phase gates using single light emitters such as diamond nitrogen vacancy centers.

Aggregation of donor nitrogen in irradiated Ni-containing synthetic diamonds

Possible mechanisms of aggregation of donor nitrogen (C center) into a pair of nitrogen atoms (A center) in Ni-containing synthetic diamonds with NV centers subjected to high temperature annealing without external pressure are discussed. It was shown that the activation energy of aggregation varied from 0.5 to 1.5eV depending on nitrogen concentration. This can be due to three different aggregation mechanisms taking place at the same time. The formation of isolated vacancies and nitrogen interstitials was studied in electron-irradiated diamonds containing different concentrations of donor nitrogen.

Model thermodynamics and the role of free-carrier energy at high temperatures: Nitrogen and boron pairing in diamond

Model thermodynamics and the role of free-carrier energy at high temperatures: Nitrogen and boron pairing in diamond

Acceptor level of nitrogen in diamond and the 270-nm absorption band

The 270-nm optical-absorption band is seen in a wide variety of diamonds but there are conflicting opinions about its relationship with the common substitutional nitrogen center. Here we use density-functional theory to show that in addition to a deep donor level, substitutional nitrogen has an acceptor level lying in the gap, which is involved in the 270 nm transition. Specifically we show that the calculated level and its stress response are consistent with those of the 270 nm defect. This indicates that substitutional nitrogen in diamond has three charge states and not two as has been commonly assumed. We also show that ${\text{N}}_{s}^{+}$ has an absorption band with a peak around 270 nm and hence can account for the lack of correlation between the 270-nm band and ${\text{N}}_{s}^{0}$ in those diamonds containing centers which compensate nitrogen. Finally, we discuss the origin of the 271-nm absorption feature and suggest that the nitrogen-hydrogen center is a strong candidate.

Diamond origin and genesis: A C and N stable isotope study on diamonds from a single eclogitic xenolith (Kaalvallei, South Africa)

In order to study the geochemistry of diamonds formed during similar growth conditions in a very localised environment in the mantle, we carried out a detailed study of the variation in δ 15N, δ 13C, N content, and N aggregation state of 35 diamonds in a single eclogite xenolith from the Kaalvallei kimberlite in South Africa. Diamond nitrogen contents determined by infrared spectroscopy range from 239 ppm to 1272 ppm, and are positively correlated with nitrogen aggregation states which vary from 11.5% to 43.7% of IaB defects. Modelling of these parameters using second order reaction kinetics suggests that the diamonds likely represent a single population which has been resident in the mantle at temperatures of 1090 °C to 1190 °C. δ 13C values of the diamonds analysed range from − 6.0‰ to − 4.2‰, while δ 15N values vary from − 8.9‰ to − 4.1‰, with no correlation between δ 13C and δ 15N. These values account for 5% and 15%, respectively, of the worldwide isotopic range for diamonds. The limited variability of C and N isotopic compositions for the diamonds analysed are compatible with a model of metasomatic diamond formation from a single, homogeneous fluid, and this is also supported by the infrared data. Although the absence of any clear correlation between δ 15N, δ 13C and diamond N content precludes the accurate identification of the fluid species involved in diamond growth, the lack of correlation may indicate the involvement of a carbonate- or CO 2-type fluid. The observed range in negative δ 15N values for all the diamonds analysed are within the limits of the so-called mantle range ( δ 15N mantle = − 5 ± 2‰) which is consistent with a mantle origin for these diamonds. Negative δ 15N is inconsistent with diamond formation from recycled (crustal) material which is enriched in 15N (i.e. positive δ 15N). In contrast, positive europium and strontium anomalies in silicate minerals of the host xenolith, as well as oxygen isotopic data which deviate from the mantle range, are consistent with a protolith consisting of recycled oceanic crust. It is therefore concluded that our data supports a model of metasomatic diamond crystallisation from a mantle-carbon source.

Dependence of nitrogen concentration in type Ib diamonds on synthesis temperature

Type Ib diamonds were grown by the temperature gradient method (TGM) at 5.5 GPa and 1500–1560 K in a china-type cubic anvil high pressure apparatus using Ni70Mn25Co5 alloy as solvent/catalyst. The concentration of nitrogen (CN) in type Ib diamonds synthesized at different synthesis temperatures was measured by a Fourier transform infrared (FTIR) spectrometer. The dependence of CN in diamond on synthesis temperature was studied. For the type Ib diamonds synthesized using Ni70Mn25Co5 as catalyst, its CN decreases along with the increase of synthesis temperature.

Metasomatic diamond growth: A multi-isotope study ( 13C, 15N, 33S, 34S) of sulphide inclusions and their host diamonds from Jwaneng (Botswana)

The formation of diamond through metasomatic events, from volatiles-enriched fluids/melts brought into pre-existing mantle rocks, has been suggested from a series of independent studies. However, the link between these hypothetical volatile-rich fluids and deep-seated mineral inclusions (mostly silicate and sulphides) entrapped in diamonds remains unclear, yet the relationship between these two species may provide the key to our understanding of diamond crystallization. In order to address the relationship between the origin and formation of diamonds and their mineral inclusions, we carried out the first coupled stable isotopic study ( δ 13C, δ 15N and multiple S-isotopes as δ 34S, δ 33S, Δ 33S) of diamonds containing sulphide inclusions, using samples from the Jwaneng kimberlite as our model system. Sulphides extracted from the present collection of 55 diamonds belong to either eclogitic (E-type, 52 diamonds) or peridotitic (P-type, 3 diamonds) paragenetic suites, as attested by their Cr and Ni content (Cr < 0.03 wt.% for E-types and Cr > 0.18 wt.% and Ni > 14 wt.% for P-types). Sulphur isotopic compositions have been measured in-situ by multicollector secondary ion mass spectrometry and reveal that peridotitic sulphide inclusions in diamonds ( n = 4) lie on the terrestrial fractionation line whereas Mass Independent sulphur isotope Fractionations (MIF) are preserved inside eclogitic sulphides inclusions (− 0.5‰ < Δ 33S < + 0.9‰, n = 33). Such large MIF values, extended here to the negative values recorded in Archean sediments, are thought to be produced through photochemical reactions in the Archean atmosphere, which implies that sulphides inclusions contain an Archean sedimentary sulphur component that was transferred to the Earth's mantle. In contrast to this isotopic dichotomy between E-type and P-type sulphides, the geochemical characteristics of their host diamonds ( δ 13C, δ 15N, N-content, N-speciation) are largely homogeneous throughout the population, and differ from silicate-bearing diamonds previously studied in the same locality. Sulphide-bearing diamonds appear to define a distinct population, which might reflect a different crystallization process characterized by carbon and nitrogen isotopic compositions falling within the range of unfractionated mantle values. The lack of a distinct isotopic signature of recycled sedimentary nitrogen and carbon in sulphide-bearing diamonds leads us to infer that sulphide-bearing Jwaneng diamonds were not derived from the same chemical reservoir as their inclusions. One possible formation mechanism that is compatible with our observations is diamond crystallization from a mantle-derived carbon-bearing fluid associated with pre-existing sedimentary sulphide minerals. This model has important implications for the interpretation of diamond ages obtained from sulphide inclusions using Re–Os systematics. Here we suggest that the incorporation of a significant amount of mantle-related sulphur during a diamond growth event into the original sulphide could lead to a re-equilibration of the Re–Os isotope composition in any inclusion, and accordingly, account for some scatter on Re–Os isochrons.

Cavity enhanced spin measurement of the ground state spin of an NV center in diamond

A key step in the use of diamond nitrogen vacancy (NV) centers for quantum computational tasks is a single shot quantum non-demolition measurement of the electronic spin state. Here, we propose a high fidelity measurement of the ground state spin of a single NV center, using the effects of cavity quantum electrodynamics. The scheme we propose is based in the one-dimensional atom or Purcell regime, removing the need for high Q cavities that are challenging to fabricate. The ground state spin of the NV center has a splitting of ≈6–10 μeV, which can be resolved in a high-resolution absorption measurement. By incorporating the center in a low-Q and low volume cavity we show that it is possible to perform single shot readout of the ground state spin using a weak laser with an error rate of ≈7×10−3, when realistic experimental parameters are considered. Since very low levels of light are used to probe the state of the spin we limit the number of florescence cycles, which dramatically reduces the measurement induced decoherence approximating a non-demolition measurement of ground state spin.

Infrared and Raman spectroscopic observations of Central African carbonado and implications for its origin

Carbonado diamonds from the Central African Republic (CAR) were investigated using spectroscopic observations. Raman spectra for a polished section of carbonado showed the average Raman frequency as 1333.0 cm −1 ; measurements 10 μm below the sample surface showed a bimodal distribution of the Raman frequency with the average at 1333.5 cm −1 . These contrasting results indicate that the carbonado interior retains considerable residual pressure. The maximum residual pressure detected in this study from the 10 μm subsurface was 0.49 GPa. From infrared (IR) absorption spectra for crushed carbonado samples, no absorption attributable to diamond was observed because absorption bands of mineral and fluid inclusions were too strongly observed. Acid leaching treatment of the crushed grains elicited IR bands assignable to intrinsic diamond vibration and nitrogen impurity in the diamonds. Nitrogen atoms in the CAR carbonado were not much aggregated and the degree of aggregation was intermediate between type Ib and type IaA. In the chemically treated samples, IR absorption bands from liquid water and carbonate were ubiquitous suggesting that the CAR carbonado samples contain fluid inclusions and are similar to diamonds containing mantle-derived fluids. The experimental results of this study suggest that the CAR carbonado originated from rapid heating event with a presence of fluid in the mantle and subsequent rapid cooling before aggregation of nitrogen impurity in the diamond lattice.