Идентификация NV-центров в синтетических флуоресцентных наноалмазах и контроль дефектности кристаллитов методом электронного парамагнитного резонанса
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2021-12-09 |
| Journal | Оптика и спектроскопия |
| Authors | В.Ю. Осипов, К.В. Богданов, François Treussart, Arfaan Rampersaud, А.В. Баранов |
| Institutions | Université Paris-Saclay, Centre National de la Recherche Scientifique |
| Citations | 3 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: NV-Center Identification in Nanodiamonds
Section titled “Technical Documentation & Analysis: NV-Center Identification in Nanodiamonds”This document analyzes the research paper “Identification of NV-centers in synthetic fluorescent nanodiamonds and control of crystallite defectiveness using electron paramagnetic resonance” to highlight relevant material science requirements and demonstrate 6CCVD’s capability to supply high-specification MPCVD diamond solutions.
Executive Summary
Section titled “Executive Summary”The research successfully synthesized high-quality fluorescent nanodiamonds (FNDs) rich in Nitrogen-Vacancy (NV-) centers, validating a critical non-optical quality control method.
- High Concentration: Achieved high NV- concentration (up to 5.5 ppm) in 100 nm FND particles derived from HPHT Ib diamond.
- Synthesis Method: NV centers were formed via high-energy electron irradiation (5 MeV) to create vacancies, followed by 800 °C annealing in an inert atmosphere.
- Quality Control: Electron Paramagnetic Resonance (EPR) spectroscopy, specifically analyzing the microwave power saturation curves of the NV- signal (g = 4.27 forbidden line), was used to assess local crystal quality.
- Minimal Defects: The saturation curve analysis confirmed that the crystal quality surrounding the NV- centers was high, comparable to bulk diamond, indicating successful mitigation of surface defects induced by mechanical grinding.
- Application Readiness: The resulting FNDs exhibit bright photoluminescence (ZPL at 637 nm) and are deemed suitable for advanced applications in nanophotonics, quantum sensing, and cellular tracking.
- Diagnostic Validation: The study confirms EPR as a reliable, non-optical method for independent assessment of NV concentration and crystal lattice quality in nanodiamonds < 150 nm.
Technical Specifications
Section titled “Technical Specifications”Hard data extracted from the experimental methodology and results sections of the paper.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Nanodiamond Size (Average) | 100 | nm | Fluorescent Nanodiamond (FND) |
| Initial HPHT Grain Size | Up to 150 | µm | Source material for FND synthesis |
| Initial Nitrogen Concentration | 150 ± 10 | ppm | In bulk HPHT Ib microcrystals |
| Max NV- Concentration (FND-3) | 5.5 | ppm | Estimated via double integration of EPR signal (g=4.27) |
| Electron Irradiation Energy | 5 | MeV | Used for vacancy creation |
| Annealing Temperature | 800 | °C | Performed in inert atmosphere |
| Minimum Irradiation Dose | 7 x 1018 | cm-2 | Corresponds to 16h exposure (FND-1) |
| EPR Measurement Frequency | 9.434 | GHz | X-band EPR |
| NV- Forbidden Line g-factor | 4.27 | - | Used for concentration and quality assessment |
| NV- Zero Phonon Line (ZPL) | 637 | nm | Peak emission wavelength |
| Fine Structure Parameter (D) | 954 x 10-4 | cm-1 | Zero-field splitting of 3A2 state |
| Surface Defect Layer Depth | 10-12 | nm | Mechanically damaged layer depth (estimated) |
Key Methodologies
Section titled “Key Methodologies”The synthesis and characterization of the fluorescent nanodiamonds (FNDs) involved precise physical and chemical processing steps:
- Source Material Preparation: Synthetic HPHT Ib microcrystals (up to 150 µm grain size, 150 ± 10 ppm N concentration) were used.
- Mechanical Reduction: Intensive crushing and grinding reduced the microcrystals to a submicron fraction (average size 104 nm).
- Size Selection: The 100 nm fraction was isolated using centrifugation in an aqueous medium.
- Vacancy Induction: The powder was irradiated with a high-energy electron beam (5 MeV) at a current density of 32 µA/cm2. Integrated exposure times varied (16 h, 32 h, 40 h) to control vacancy density.
- NV Center Formation: Post-irradiation annealing was performed at 800 °C in an inert atmosphere to mobilize vacancies, allowing them to bind with isolated nitrogen atoms (P1 centers) to form NV- centers.
- Purification: Intensive chemical cleaning using boiling acids was performed to remove metallic impurities (e.g., iron complexes) that interfere with optical and magnetic measurements.
- EPR Characterization: EPR spectra were recorded at 9.5 GHz. Concentration was determined by double integration of the g = 4.27 signal. Crystal quality was assessed by measuring the peak intensity (Ipp) dependence on microwave power (Pmw) saturation curves.
- Optical Characterization: Photoluminescence (PL) spectra were measured using 532 nm laser excitation to confirm NV- emission (600-820 nm).
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The research demonstrates the critical need for high-quality, precisely doped diamond material for advanced quantum and nanophotonic applications. 6CCVD provides the necessary MPCVD substrates and engineering expertise to replicate and extend this work, offering superior control over nitrogen incorporation and crystal structure compared to the HPHT starting material used in the study.
| Research Requirement | 6CCVD Solution & Capability | Technical Advantage & Sales Proposition |
|---|---|---|
| High-Purity Starting Material | Optical Grade Single Crystal Diamond (SCD) | Our SCD is grown via MPCVD, offering ultra-low defect density and minimal strain, crucial for maximizing NV coherence times (T2 and T2*). We provide precise thickness control (0.1 µm - 500 µm) for optimal electron beam penetration and vacancy creation. |
| Precise Nitrogen Doping | Custom N-Doped SCD/PCD | We offer tailored nitrogen concentrations (ppm level) during the MPCVD growth process. This allows researchers to optimize the starting P1 center density, ensuring maximum NV- yield after irradiation and annealing, directly supporting the methodology described in the paper. |
| Large-Scale Production | High-Purity Polycrystalline Diamond (PCD) | For applications requiring large-area sensing arrays or high-volume nanodiamond production, 6CCVD supplies PCD wafers up to 125 mm diameter. Our PCD offers excellent uniformity and high purity, suitable for subsequent grinding and processing. |
| Surface Quality for Coherence | Advanced Polishing Services | The paper highlights the detrimental effect of mechanical damage (grinding) on surface defects. 6CCVD guarantees SCD surfaces polished to Ra < 1 nm and inch-size PCD to Ra < 5 nm, minimizing surface strain and maximizing the coherence of near-surface NV centers. |
| Device Integration & Testing | Custom Metalization and Fabrication | We offer in-house metalization (Au, Pt, Pd, Ti, W, Cu) for integrating diamond substrates into microwave (EPR/ODMR) or micro-optical devices. This capability is essential for researchers transitioning from material synthesis to functional device prototyping. |
| Global Logistics | Worldwide Shipping (DDU/DDP) | 6CCVD ensures reliable, global delivery of sensitive diamond materials, offering DDU (Delivered Duty Unpaid) as default and DDP (Delivered Duty Paid) options for seamless customs clearance. |
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD team specializes in defect engineering and material optimization for quantum applications. We can assist researchers in selecting the optimal diamond substrate (SCD vs. PCD), determining the appropriate nitrogen doping level, and advising on post-processing protocols (irradiation and annealing temperatures) to maximize NV- yield and coherence for similar NV-Center Quantum Sensing and Nanophotonics projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
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 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 has the form of a curve with saturation and subsequent decay, and 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 more sensitive to changes in particle size in the submicron range and the appearance of near-surface defects obtained during mechanical processing.