Identification of NV Centers in Synthetic Fluorescent Nanodiamonds and Control of Defectiveness of Crystallites Using Electron Paramagnetic Resonance
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2022-01-01 |
| Journal | Оптика и спектроскопия |
| Authors | V. Yu. Osipov, Bogdanov K.V., François Treussart, Arfaan Rampersaud, А. В. Баранов |
| Institutions | Centre National de la Recherche Scientifique, Université Paris-Saclay |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: NV Center Identification in Fluorescent Nanodiamonds
Section titled “Technical Documentation & Analysis: NV Center Identification in Fluorescent Nanodiamonds”6CCVD specializes in providing high-quality, engineered MPCVD diamond materials (SCD, PCD, BDD) essential for advanced quantum, optical, and sensing applications. This analysis connects the findings of the research paper, “Identification of NV Centers in Synthetic Fluorescent Nanodiamonds and Control of Defectiveness of Crystallites Using Electron Paramagnetic Resonance,” directly to 6CCVD’s material capabilities and customization services.
Executive Summary
Section titled “Executive Summary”This study successfully validates Electron Paramagnetic Resonance (EPR) spectroscopy as a critical non-optical diagnostic tool for characterizing Nitrogen Vacancy (NV) centers in synthetic fluorescent nanodiamonds (FNDs).
- Defect Engineering Success: High concentrations of NV- centers (up to 5.5 ppm) were achieved in 100 nm FND particles derived from HPHT Ib diamond precursors via 5 MeV electron irradiation and 800 °C annealing.
- Quality Assessment: The shape of the EPR signal saturation curves (peak intensity vs. square root of microwave power) provides a qualitative estimate of the crystalline quality and local environment surrounding the NV- centers.
- Correlation Established: A strong correlation was found between the integral intensity of the forbidden EPR transition (g = 4.27) and the overall luminescence intensity (600-820 nm), confirming EPR as a reliable method for selecting high-fluorescence diamond powders.
- Material Suitability: The crystalline quality of the 100 nm FNDs was found to be comparable to bulk diamond, making them highly suitable for applications in nanophotonics, optical secure communication, and biomedical sensing.
- Surface Defect Control: Mechanical grinding to 100 nm did not introduce a significant number of surface defects (multivacancies) that would strongly quench NV- luminescence, demonstrating control over the defectiveness of the crystallites.
Technical Specifications
Section titled “Technical Specifications”The following hard data points were extracted from the research paper detailing the material properties and experimental conditions:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Nanodiamond Average Size | 100 | nm | FND particles studied |
| Precursor Nitrogen Concentration | 150 ± 10 | ppm | Original HPHT Ib microcrystals |
| Electron Beam Irradiation Energy | 5 | MeV | Used for vacancy creation |
| Maximum Exposure Dose (FND-3) | 7.1018 | cm-2 | Minimum nominal dose |
| Annealing Temperature | 800 | °C | Performed in inert atmosphere |
| Maximum NV- Concentration | 5.5 | ppm | Achieved in FND-3 sample |
| EPR Measurement Frequency | 9.444 | GHz | X-band spectroscopy |
| EPR Forbidden Transition g-factor | 4.27 | - | Associated with NV- centers (Δms = 2) |
| NV- Zero-Phonon Line (ZPL) | 637 | nm | Luminescence peak |
| Spin Hamiltonian Parameter D | 954.10-4 | cm-1 | Fine structure parameter (2.87 GHz gap) |
| Surface Defect Layer Depth | 5-10 | nm | Near-surface layer thickness |
Key Methodologies
Section titled “Key Methodologies”The experimental process involved precise material selection, mechanical reduction, defect creation, and rigorous purification:
- Precursor Selection: Synthetic HPHT Ib microcrystalline diamond (grain size up to 150 µm) with a high intrinsic nitrogen concentration (150 ± 10 ppm) was chosen as the starting material.
- Mechanical Processing: Intensive crushing and grinding were performed to reduce the microcrystals to a submicron fraction.
- Size Separation: The desired 100 nm average particle size was selected by centrifugation in an aqueous medium (particle distribution width at half maximum of ~76 nm).
- Vacancy Induction: The FND powder was irradiated with a high-energy electron beam (5 MeV, 32 µA/cm2) for integral periods up to 40 hours to create lattice vacancies.
- NV Center Formation: Subsequent annealing at 800 °C in an inert atmosphere was performed to mobilize vacancies, allowing them to be captured by isolated nitrogen impurities (P1 centers) to form NV- centers.
- Chemical Purification: The annealed samples were subjected to intensive chemical purification in boiling acids to remove parasitic metal impurities, particularly iron-containing complexes, which can quench fluorescence.
- Characterization: Defect concentration and crystal quality were assessed using X-band EPR spectroscopy (9.5 GHz) and luminescence spectroscopy (532 nm excitation).
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The research highlights the critical need for high-quality, defect-engineered diamond materials for quantum and nanophotonics applications. 6CCVD provides the foundation for replicating and advancing this research, offering superior MPCVD diamond plates and wafers for controlled defect creation.
Applicable Materials for NV Center Research
Section titled “Applicable Materials for NV Center Research”To replicate or extend the high-quality NV center formation demonstrated in this paper, 6CCVD recommends the following materials, depending on the application scale:
| 6CCVD Material | Description & Application | Relevance to Research |
|---|---|---|
| Optical Grade SCD | High-purity Single Crystal Diamond (SCD) plates, low strain, ideal for minimizing spectral broadening and maximizing NV coherence time. | Provides the lowest defect background for controlled nitrogen incorporation and subsequent NV formation via irradiation/annealing. |
| Nitrogen-Doped SCD | SCD plates grown with controlled nitrogen incorporation (P1 centers) during the MPCVD process. | Essential for precise control over the precursor nitrogen concentration (analogous to the 150 ppm HPHT precursor used). |
| High-Purity PCD | Polycrystalline Diamond (PCD) wafers up to 125 mm diameter, suitable for large-area sensing or high-volume FND precursor production. | Offers cost-effective, large-scale starting material for grinding into FNDs, especially where micron-scale crystal quality is acceptable. |
Customization Potential for Quantum Applications
Section titled “Customization Potential for Quantum Applications”While this study focused on 100 nm particles, the underlying requirement is a high-quality diamond lattice. 6CCVD’s customization capabilities are essential for integrating NV centers into functional devices:
- Custom Dimensions & Thickness: 6CCVD supplies SCD and PCD plates in custom dimensions, with thicknesses ranging from 0.1 µm to 500 µm for active layers, and substrates up to 10 mm thick. This is crucial for fabricating thin membranes or bulk quantum sensors.
- Ultra-Low Roughness Polishing: The paper emphasizes that surface defects (within 5-10 nm) can affect NV center characteristics. 6CCVD guarantees Ra < 1 nm polishing for SCD and Ra < 5 nm for inch-size PCD, minimizing surface-induced strain and defect quenching.
- Integrated Metalization: For integrating NV-based sensors into microwave circuits (as required for EPR/ODMR), 6CCVD offers in-house metalization services, including Ti, Pt, Au, Pd, W, and Cu contacts, tailored to specific device geometries.
- Controlled Doping: We offer precise control over Boron (BDD) and Nitrogen doping during MPCVD growth, allowing researchers to optimize the charge state (NV0 vs. NV-) and concentration profile required for specific quantum experiments.
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD team provides authoritative professional support for material selection and process optimization for NV Center Defect Engineering projects. We assist clients in defining the optimal precursor material (SCD vs. PCD, doping level) and post-processing requirements (e.g., surface termination, metalization) necessary to achieve target NV concentrations and coherence times.
Call to Action: For custom specifications or material consultation regarding high-quality diamond precursors for quantum sensing, nanophotonics, or biomedical applications, visit 6ccvd.com or contact our engineering team directly. We offer global shipping (DDU default, DDP available) to ensure timely delivery of your specialized materials.
View Original Abstract
A 100 nm synthetic diamond particle with a large (> 4 ppm) amount of nitrogen vacancy (NV) centers has been studied. The latter exhibit lines associated with forbidden Delta m_s = 2 and allowed Delta m_s = 1 transitions in the electron paramagnetic resonance (EPR) spectra of the ground state of the NV (-) center. The luminescence intensity of particles in the range 550-800 nm increases with an increase in the irradiation dose of 5 MeV electrons and correlates with the integrated intensity of the peak EPR line with a g-factor g = 4.27. This value is used to estimate the concentration of NV (-) centers and to select diamond powders with the highest fluorescence intensity. The dependence of the EPR signal intensity of the Delta m_s = 2 transition of the NV (-) center on the microwave power that increases before decaying rather well characterizes the crystal quality of the local environment of the centers under study in these particles. The intensity of the x, y Delta m_s = 1 transition (at ~ 281.2 mT, 9.444 GHz) turns out to be sensitive to changes in particle size in the submicron range and the appearance of near-surface defects obtained during mechanical processing. Keywords: luminescence, nitrogen vacancy centers, synthetic diamond, nanocrystals, electron paramagnetic resonance.