| Metadata | Details |
|---|
| Publication Date | 2023-01-07 |
| Journal | Nanomaterials |
| Authors | S. I. Kudryashov, G. Yu. Kriulina, П. А. Данилов, Evgeny V. Kuzmin, А. Н. Кириченко |
| Institutions | Lomonosov Moscow State University, P.N. Lebedev Physical Institute of the Russian Academy of Sciences |
| Citations | 5 |
| Analysis | Full AI Review Included |
This study investigates the precise control of nitrogen impurity center transformations in natural diamond using visible-range femtosecond (fs) laser pulses, focusing on vacancy-mediated mechanisms for engineering Nitrogen-Vacancy (NV) centers.
- Core Achievement: Demonstrated nanoscale control over the aggregation, dissociation, and splitting of highly aggregated nitrogen centers (A, B1, N3a, H3, H4) deep within bulk natural IaA+B diamond.
- Mechanism Confirmation: The structural modifications are driven by intrinsic and photo-generated vacancies (V) created by the non-linear absorption of the fs laser pulses.
- Low Energy Regime (Aggregation): Incident pulse energies less than 0.6 µJ promote vacancy-mediated aggregation, leading to an initial rise in vacancy-enriched centers (N3a, H3, H4).
- High Energy Regime (Splitting/Dissociation): Above the threshold energy (0.6 µJ), highly aggregated centers undergo dissociation and concerted vacancy-driven splitting, resulting in a predominant yield of desired NV centers (NV0 and NV-).
- Visualization Technique: 3D scanning confocal photoluminescence (PL) microspectroscopy (405 nm and 532 nm excitation) was used to map these structural changes, confirming the depth-dependent formation of NV centers.
- Engineering Relevance: Provides a robust, non-thermal method for bulk inscription and precise defect engineering of NV centers in high-nitrogen natural diamond, critical for quantum technology applications.
| Parameter | Value | Unit | Context |
|---|
| Diamond Material | Natural IaA+B | N/A | High nitrogen content, weakly radioactive |
| Nitrogen (A centers) | ~600 | ppm | [A(2N)] average concentration |
| Nitrogen (B1 centers) | ~90 | ppm | [B1(4NV)] average concentration |
| Laser Wavelength | 515 | nm | Femtosecond pulse source |
| Pulse Duration | 0.3 | ps | Ultrashort pulse regime |
| Repetition Rate | 100 | kHz | Pulse delivery frequency |
| Incident Pulse Energy Range | 0.1 to 1.6 | µJ | Used for bulk micro-inscription |
| NV Center Threshold Energy (Eth) | 0.6 | µJ | Energy required for transition to NV center formation |
| Focusing Objective NA | 0.25 | N/A | Numerical Aperture |
| Focal Spot Radius (1/e) | 2 | µm | Estimated intensity radius |
| Inscription Depth | 20-50 | µm | Depth of photoluminescent microtracks |
| Exposure Time Range | 10 to 240 | s | Corresponds to 1 M to 24 M pulses |
| PL Excitation Wavelengths | 405, 532 | nm | Confocal microspectroscopy pump sources |
| Measurement Temperature (RT) | 25 | °C | Room Temperature analysis |
| Measurement Temperature (LNT) | -120 | °C | Liquid Nitrogen Cooling Temperature analysis |
| Raman Shift (Diamond) | 1332 | cm-1 | Optical phonon band |
| NV- ZPL | 637 | nm | Zero Phonon Line |
| NV0 ZPL | 575 | nm | Zero Phonon Line |
- Material Characterization: The natural IaA+B diamond (4 x 4 x 4 mm3) was initially characterized using FT-IR spectroscopy to quantify nitrogen aggregates (A, B1, B2 centers) and UV-near-IR transmission spectroscopy to identify existing color centers (N3, NV, V0).
- Femtosecond Laser Inscription: A 515 nm, 0.3 ps laser was focused via a 0.25 NA micro-objective into the bulk of the diamond (z~360 µm nominal focus). A matrix of photoluminescent microtracks was created in the prefocal region (20-50 µm depth) by systematically varying the pulse energy (0.1 to 1.6 µJ) and exposure time (10 to 240 s).
- 3D Confocal PL Microspectroscopy: Post-irradiation analysis was performed using 3D scanning confocal Raman/PL microspectroscopy (Renishaw inVia InSpect).
- Dual-Wavelength Probing: Two excitation wavelengths were used: 532 nm (primarily probing NV0, NV-, V0) and 405 nm (providing detailed spectral variation of N3a, H3, H4, and NV centers).
- Temperature-Dependent Analysis: Measurements were conducted at both Room Temperature (RT, 25 °C) and Liquid Nitrogen Cooling Temperature (LNT, -120 °C) to differentiate between charge states (e.g., NV0 vs. NV-) and assess vacancy lability.
- Defect Transformation Analysis: PL spectra were normalized (micromark/background) to isolate laser-induced changes. The analysis focused on the transition from highly aggregated centers (N3a, H3, H4) to lowly aggregated NV centers, correlating the conversion yield with laser energy and exposure time.
| Industry/Sector | Application/Product Relevance | Technical Benefit |
|---|
| Quantum Sensing & Computing | Fabrication of solid-state qubits (NV- centers) in diamond. | Enables precise, high-density, 3D placement of NV centers deep within the bulk material, crucial for robust quantum device architectures. |
| High-Security Marking | Permanent, bulk inscription of photoluminescent identifiers (e.g., QR codes) in high-value natural diamonds. | Provides tamper-proof traceability and authentication using stable, laser-written color centers visible via PL. |
| Defect Engineering | Controlled creation and manipulation of specific point defects (NV, H3, H4) in wide-bandgap semiconductors. | Offers a non-thermal, high-spatial-resolution method to study and optimize vacancy-mediated reactions, improving synthetic diamond growth recipes. |
| Nanophotonics & Integrated Optics | Creation of localized light sources and optical components (waveguides, resonators) within the diamond matrix. | Utilizes the high refractive index and stability of diamond, combined with the emission properties of the engineered NV centers. |
| Radiation Detection | Development of diamond-based radiation detectors utilizing stable, laser-induced color centers. | The controlled introduction of defects can tailor the material’s response to ionizing radiation. |
View Original Abstract
Natural IaA+B diamonds were exposed in their bulk by multiple 0.3 ps, 515 nm laser pulses focused by a 0.25 NA micro-objective, producing in the prefocal region (depth of 20-50 μm) a bulk array of photoluminescent nanostructured microtracks at variable laser exposures and pulse energies. These micromarks were characterized at room (25°) and liquid nitrogen cooling (−120 °C) temperatures through stationary 3D scanning confocal photoluminescence (PL) microspectroscopy at 405 and 532 nm excitation wavelengths. The acquired PL spectra exhibit a linearly increasing pulse-energy-dependent yield in the range of 575 to 750 nm (NV0, NV− centers) at the expense of the simultaneous reductions in the blue-green (450-570 nm; N3a, H4, and H3 centers) and near-IR (741 nm; V0 center) PL yield. A detailed analysis indicates a low-energy rise in PL intensity for B2-related N3a, H4, and H3 centers, while at higher, above-threshold pulse energies it decreases for the H4, H3, and N3a centers, converting into NV centers, with the laser exposure effect demonstrating the same trend. The intrinsic and (especially) photo-generated vacancies were considered to drive their attachment as separate species to nitrogen centers at lower vacancy concentrations, while at high vacancy concentrations the concerted splitting of highly aggregated nitrogen centers by the surrounding vacancies could take place in favor of resulting NV centers.
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