Effects of silver nanoparticles on Raman spectrum and fluorescence enhancement of nano-diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-01-01 |
| Journal | Acta Physica Sinica |
| Authors | Lishuang Liu, Xiujian Chou, Tao Chen, Lining Sun |
| Citations | 4 |
| Analysis | Full AI Review Included |
Technical Analysis and Material Solutions for Plasmon-Enhanced Quantum Diamond Devices
Section titled âTechnical Analysis and Material Solutions for Plasmon-Enhanced Quantum Diamond Devicesâ6CCVD Documentation Reference: APS-65-197301 Title: Effects of silver nanoparticles on Raman spectrum and fluorescence enhancement of nano-diamond Focus: Localized Surface Plasmon Resonance (LSPR) enhancement of Nitrogen-Vacancy (NV) center fluorescence and Raman scattering in nano-diamond.
Executive Summary
Section titled âExecutive SummaryâThis research demonstrates a highly effective method for enhancing the intrinsic properties of nano-diamond (ND) containing Nitrogen-Vacancy (NV) color centers by leveraging plasmonic effects. This technique is critical for applications requiring high-sensitivity quantum sensing and bio-detection.
- Core Achievement: Significant enhancement (Surface Enhanced Raman Scattering, SERS, and Surface Enhanced Fluorescence, SEF) of ND/NV properties achieved by integrating the diamond film with Silver (Ag) nanoparticles (NPs).
- Mechanism Confirmation: Enhancement is driven by Localized Surface Plasmon Resonance (LSPR), which increases the local electric field intensity around the NV centers.
- Raman Enhancement: The characteristic diamond Raman peak (1332.4 cm-1) shows increased intensity proportional to low Ag NP mass concentration, verifying plasmonic coupling.
- Optimal Performance: Maximum fluorescence intensity and quantum efficiency (QE) were achieved at an optimal Ag NP concentration of approximately 5 wt%.
- Efficiency Gains: The fluorescence Quantum Efficiency increased substantially (from 2.44% to 8.42% at 5 wt%), correlating directly with a significant reduction in fluorescence lifetime (Ïm).
- Engineering Implication: The study highlights the necessity of precise control over the distance between the NV centers and the plasmonic material to maximize the radiative transition rate and suppress non-radiative quenching.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the quantitative data and experimental findings crucial for replicating or advancing this research.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Material | Nano-diamond (MSY 0-0.05) | N/A | Used for NV center studies |
| Diamond Average Size | 52.8 | nm | Most grains measured < 60 nm |
| Raman Intrinsic Peak | 1332.4 | cm-1 | Diamond characteristic peak |
| Optimal Ag Concentration (Intensity) | 5 | wt% | Maximum observed light intensity |
| Concentration for Quenching | > 7 | wt% | Concentration at which light intensity begins to decline (quenching) |
| Initial Quantum Efficiency (QE) | 2.44 | % | Measured at 0.1 wt% Ag NP concentration |
| Maximum Quantum Efficiency (QE) | 8.42 | % | Measured at 5 wt% Ag NP concentration |
| Initial Fluorescence Lifetime (Ïm) | 3.725 | ns | Measured at 0.02% Ag NP concentration |
| Reduced Fluorescence Lifetime (Ïm) | 1.896 | ns | Measured at 0.2% Ag NP concentration |
| Excitation Wavelength (Raman/PL) | 514.5 / 514 ± 5 | nm | Continuous wave / Pulsed excitation |
| NV0 Fluorescence Peak | 577 | nm | Characteristic Zero-Phonon Line (ZPL) measured |
| PL Detection Range | 500 - 800 | nm | Full photoluminescence band recorded |
Key Methodologies
Section titled âKey MethodologiesâThe experiment successfully fabricated and characterized plasmon-enhanced diamond films using precise synthesis and advanced spectroscopy.
- Material Preparation:
- Specific masses of commercial nano-diamond (MSY 0-0.05) and sodium silicate were mixed and dispersed in deionized water.
- Silver (Ag) nano-powder was introduced to the mixture, creating varying mass concentrations (0.1 wt% to 9 wt%).
- The composite liquid was subjected to ultrasonic oscillation for 1 h at ambient temperature to prevent agglomeration and achieve uniform suspension.
- Thin Film Fabrication:
- The uniform suspension was spin-coated onto standard Si substrates.
- Films were allowed to rest for 2.5 h at room temperature for complete water evaporation, forming the mixed thin-film samples.
- Structural and Compositional Analysis:
- Field Emission Scanning Electron Microscopy (FESEM, JSM-6700F) was used to characterize morphology and verify the uniform distribution of Ag NPs at low concentrations (0.5 wt% and 1 wt%).
- Energy Dispersive Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS) confirmed the presence of Ag, C, and Si (from the substrate) elements and verified the polycrystalline structure (D(111), D(220), D(311) planes).
- Spectroscopic Measurements:
- Raman Spectroscopy: Measured using a Renishaw InVia system with a 514.5 nm laser (5 mW power, 10 s integration time).
- Fluorescence (PL) Measurement: Measured using a Leika DM 2000 microscope and an Edinburgh Instruments FLSP920 system (spectrometer).
- Lifetime (Ïm) Measurement: Conducted using Time-Correlated Single Photon Counting (TCSPC) setup.
- Excitation: Picosecond supercontinuum fiber laser (SuperK EXTREME, NKT Photonics).
- Wavelengths: 514 ± 5 nm, 633 ± 5 nm, and 830 ± 5 nm.
- Frequency: 13 MHz pulse frequency.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research relies fundamentally on high-quality diamond material with controllable impurity centers (NV). 6CCVD, as an expert MPCVD producer, is uniquely positioned to supply the advanced diamond wafers and customization services necessary to industrialize and scale this plasmon-enhanced quantum technology.
Applicable Materials
Section titled âApplicable MaterialsâThe foundation of this successful plasmonic enhancement is the quality and stability of the underlying diamond material hosting the NV centers.
| Research Requirement | 6CCVD Recommended Material | Material Rationale & Advantage |
|---|---|---|
| Stable NV Hosting Substrate | Optical Grade Single Crystal Diamond (SCD) | SCD offers superior purity and crystallographic orientation compared to the nano-diamond powder used. This minimizes background noise and maximizes NV center coherence time and quantum yield. |
| High Surface Area Sensing Platform | Optical Grade Polycrystalline Diamond (PCD) | For large-area sensing < 125 mm, PCD substrates provide the necessary scale. 6CCVD can supply fine-grained PCD with low roughness ideal for subsequent thin-film deposition or NP integration. |
| Surface Modification Base | SCD Wafers (Custom Thickness) | Used for subsequent NV center creation via controlled ion implantation, followed by necessary high-temperature annealing (not detailed in this paper, but critical for creating high-density NV centers). 6CCVD supplies SCD from 0.1 ”m to 500 ”m thick. |
Customization Potential
Section titled âCustomization PotentialâThe paperâs findingsâthat enhancement is highly dependent on the spatial relationship between the Ag NPs and the diamond surfaceâdemands precise engineering control beyond simple solution mixing. 6CCVD offers solutions for integrated plasmonic structures.
- Integrated Metalization: While the paper used external Ag NPs, 6CCVD offers in-house capability for precise deposition and patterning of plasmonic metals directly onto the diamond surface, including Au, Pt, Pd, Ti, W, and Cu. This allows engineers to create stable, controlled nanostructures (e.g., plasmonic antennas or gratings) crucial for tuning the LSPR frequency and ensuring optimal coupling distance, thereby preventing non-radiative quenching.
- Custom Dimensions and Thin Films: 6CCVD provides custom diamond plate dimensions up to 125 mm (PCD) and controls layer thickness down to 0.1 ”m. This is essential for devices requiring integrated optical paths or high-quality thin-film deposition.
- Ultra-Low Surface Roughness: LSPR effects are highly sensitive to surface morphology. 6CCVD guarantees ultra-smooth polishing capabilities: Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD. This guarantees reliable and repeatable performance for surface-sensitive experiments like SERS and SEF.
Engineering Support
Section titled âEngineering SupportâThe optimization of plasmonic couplingâbalancing LSPR field enhancement against non-radiative energy transferâis a complex challenge. 6CCVDâs in-house PhD engineering team specializes in diamond material science and can assist researchers in material selection, orientation, and surface preparation for similar Surface-Enhanced Quantum Sensing projects. We offer consultation on:
- Selecting the optimal diamond grade and orientation for specific NV concentration requirements.
- Design considerations for custom metalization recipes to match plasmon resonance frequency with the target NV ZPL (577 nm, 637 nm).
- Achieving the high-quality surface finishes necessary for reliable integration of nanostructures.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
The nano-diamond has been a hot topic in the field of nano-science and nanotechnology for its optical properties. Much effort has been devoted to improving the fluorescence and Raman scattering intensity of nitrogen-vacancy (NV) center in nano-diamond by using plasmon resonance effect in sensing area. A combination of Ag nanoparticle and diamond can not only take advantage of the stability and biocompatibility of diamond, but also enhance the local electric field around NV center through the Ag nanoparticles, thereby speeding up the radiation of the fluorescent near the surface of the substrate, improving the strength and stability of the fluorescence, and greatly broadening the application areas of Raman spectroscopy. In this paper, we mix the nano-diamonds with Ag nanoparticles to improve the fluorescence and Raman scattering intensity on the basis of the localized surface plasmon resonance effect. The influences of Ag mass concentration on the Raman spectrum and fluorescence intensity are investigated. The results show that when the concentration of nano-Ag nanoparticles reaches up to 5 wt%, the light intensity becomes saturated, but the concentration further increases up to a value more than 7 wt% the light intensity begins to decline. Then the corresponding radiative transition rate and the fluorescence quantum efficiency are investigated, and based on these researches, influences and mechanism of surface plasmon resonance (SPR) enhancement are discussed thoroughly. We deduced that the fluorescence enhancement is mainly due to the enhanced surface plasmon field caused by transfer of surface plasmon resonance energy and the energy transfer between surface plasmon and excited state of NV centers. When the concentration of Ag nanoparticles reaches an appropriate value, a suitable distance between metal nanoparticles and diamond is obtained, thereby ensuring the strong local electric field forming on the metal surface, accelerating the emitting photons of diamond in the excited state, and also suppressing the transfer of non-radiative energy, eventually leading to the increase of diamond fluorescence emission intensity.