Chemically Tuning Room Temperature Pulsed Optically Detected Magnetic Resonance
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-06-17 |
| Journal | Journal of the American Chemical Society |
| Authors | Sarah K. Mann, Angus Cowley-Semple, Emma Bryan, Zhongping Huang, Sandrine Heutz |
| Institutions | University of Glasgow, Imperial College London |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Chemically Tuning Room Temperature Pulsed Optically Detected Magnetic Resonance
Section titled âTechnical Documentation & Analysis: Chemically Tuning Room Temperature Pulsed Optically Detected Magnetic ResonanceâExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates the optimization of quantum sensing metrics using chemically tunable molecular spins, providing a complementary platform to traditional solid-state defects like the Nitrogen-Vacancy (NV) center in diamond.
- Record Contrast Achieved: Room-temperature pulsed Optically Detected Magnetic Resonance (ODMR) contrast reached 40% using 6,13-diazapentacene (DAP), significantly exceeding the typical 30% contrast of the NV center in diamond.
- Mechanism Elucidated: The enhanced contrast is driven by accelerated anisotropic intersystem crossing (ISC), facilitated by nitrogen substitution, which creates a greater difference between âbrightâ and âdarkâ spin sublevels.
- High-Precision Dynamics: A comprehensive pulsed ODMR methodology was developed and benchmarked, allowing for the unambiguous extraction of nine triplet kinetic parameters (decay rates $k_i$, spin-lattice relaxation rates $w_{ij}$, and initial populations $P_i$) with high precision at room temperature.
- Coherence Maintained: The room-temperature coherence time (T2) for DAP was measured at 1.71 ± 0.05 ”s, comparable to pentacene, confirming that chemical modification did not adversely affect spin coherence.
- Scalability Demonstrated: High-contrast pulsed ODMR was successfully translated to self-assembled DAP:PTP nanocrystals (mean diameter 447 nm), highlighting the potential for synthesizing deployable quantum sensors at scale.
- 6CCVD Relevance: While the paper focuses on molecular systems, the NV center in diamond remains the critical benchmark. 6CCVD provides the ultra-high purity Single Crystal Diamond (SCD) required for state-of-the-art NV quantum sensing and ideal substrates for integrating novel molecular spin systems.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research paper, focusing on key performance metrics and material parameters.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum ODMR Contrast | 40 | % | DAP:PTP 100 nm thin films (0.5% doped) |
| NV Center Benchmark Contrast | 30 | % | Typical contrast for NV centers in diamond |
| Coherence Time (T2) - Crystal | 1.71 ± 0.05 | ”s | DAP:PTP single crystal (Hahn-echo) |
| Coherence Time (T2) - Nanocrystal | 1.46 ± 0.07 | ”s | DAP:PTP nanocrystals |
| Zero-Field Splitting (D) | 1390.5 | MHz | Best-fit parameter for DAP |
| Zero-Field Splitting (E) | -84.9 | MHz | Best-fit parameter for DAP |
| Fastest Depopulation Rate ($k_x$) | 24.9 ± 0.2 x 104 | s-1 | DAP:PTP, approximately 10x faster than Pentacene |
| Nanocrystal Mean Diameter | 447 | nm | Self-assembled DAP:PTP nanocrystals |
| Thin Film Thickness | 100 | nm | Optimized DAP:PTP thin films |
| Operating Temperature | 293 | K | Room Temperature |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relied on advanced ODMR techniques and precise material synthesis to characterize and optimize the molecular spin dynamics.
- Material Synthesis: 6,13-diazapentacene (DAP) was used as the guest molecule, doped into a p-terphenyl (PTP) host matrix, prepared as single crystals, 100 nm thin films, and self-assembled nanocrystals.
- Continuous-Wave (cw) ODMR: Used to determine the zero-field splitting parameters (D and E) and characterize the hyperfine coupling to the 14N nuclei in the DAP molecule.
- Pulsed ODMR Contrast Optimization: Performed on thin films to maximize the optical-spin contrast, achieving 40% by capitalizing on the accelerated anisotropic intersystem crossing (ISC) dynamics.
- Coherent Control: Optically detected Hahn-echo sequences were employed to measure the room-temperature coherence time (T2) and observe Electron Spin Echo Envelope Modulation (ESEEM) resulting from coupling to 14N nuclei.
- Triplet Spin Dynamics Extraction: A total of 22 distinct time-dependent pulsed ODMR measurements (using two sequences, A and B, and six initialization states) were globally fitted to unambiguously extract the full set of nine triplet kinetic parameters ($k_i$, $w_{ij}$, $P_i$).
- Nanocrystal Integration: DAP:PTP nanocrystals were grown via the reprecipitation method and drop-cast onto silicon substrates, demonstrating the translation of high-contrast pulsed ODMR to deployable nanoscale sensors.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research highlights the continued importance of solid-state defects like the NV center as performance benchmarks, while also demonstrating the need for high-quality substrates and advanced processing for integrating novel quantum materials. 6CCVD is uniquely positioned to supply the foundational diamond materials and customization services required to replicate, benchmark, and extend this research.
Applicable Materials
Section titled âApplicable Materialsâ| Research Requirement / Application | 6CCVD Material Recommendation | Technical Rationale |
|---|---|---|
| NV Center Benchmarking (High T2, Low Strain) | Optical Grade Single Crystal Diamond (SCD) | Ultra-high purity SCD is essential for maximizing the coherence time (T2) and sensitivity of NV centers, providing the most reliable benchmark platform. |
| Substrate Integration (Molecular Films/Nanocrystals) | High-Quality Polycrystalline Diamond (PCD) | Offers large area coverage (up to 125mm diameter) and superior thermal management compared to silicon, ideal for integrating molecular thin films or nanocrystals into high-power quantum devices. |
| Electrochemical/High-Power Applications | Boron-Doped Diamond (BDD) | Available in SCD or PCD formats, BDD provides tunable conductivity, useful for on-chip microwave delivery or electrochemical quantum sensing setups. |
Customization Potential
Section titled âCustomization PotentialâThe integration of molecular spins into functional quantum devices requires precise material engineering, a core capability of 6CCVD.
| Paper Requirement / Future Need | 6CCVD Customization Service | Specification Range |
|---|---|---|
| Substrate Size & Thickness | Custom Dimensions & Thickness Control | Plates/wafers up to 125mm (PCD). SCD thickness: 0.1”m - 500”m. Substrates up to 10mm. |
| On-Chip Microwave Control | Internal Metalization Services | Deposition of Au, Pt, Pd, Ti, W, Cu for fabricating microwave antennas and control lines required for pulsed ODMR sequences (e.g., $\pi/2$ and $\pi$ pulses). |
| Optical Interface Quality | Ultra-Smooth Polishing | Achievable surface roughness Ra < 1nm (SCD) and Ra < 5nm (Inch-size PCD), critical for minimizing scattering losses in optical readout systems. |
| Device Structuring | Precision Laser Cutting | Custom shaping and dicing of diamond wafers to match specific experimental geometries or device footprints. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in MPCVD growth and diamond processing for quantum technologies. We offer authoritative professional support for projects involving:
- Material Selection: Assisting researchers in selecting the optimal diamond grade (SCD purity, PCD grain size, BDD doping level) to maximize spin coherence and device performance for ODMR and quantum sensing applications.
- Interface Engineering: Consulting on surface preparation and metalization strategies for integrating novel molecular spin systems or thin films onto diamond substrates, ensuring robust device performance.
- Global Logistics: Providing reliable global shipping (DDU default, DDP available) to ensure sensitive materials reach your lab quickly and safely.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Optical detection of magnetic resonance enables spin-based quantum sensing with high spatial resolution and sensitivityâeven at room temperatureâas exemplified by solid-state defects. Molecular systems provide a complementary, chemically tunable, platform for room-temperature optically detected magnetic resonance (ODMR)-based quantum sensing. A critical parameter governing sensing sensitivity is the optical contrastâi.e., the difference in emission between two spin states. In state-of-the-art solid-state defects such as the nitrogen-vacancy center in diamond, this contrast is approximately 30%. Here, capitalizing on chemical tunability, we show that room-temperature ODMR contrasts of 40% can be achieved in molecules. Using a nitrogen-substituted analogue of pentacene (6,13-diazapentacene), we enhance contrast compared to pentacene and, by determining the triplet kinetics through time-dependent pulsed ODMR, show how this arises from accelerated anisotropic intersystem crossing. Furthermore, we translate high-contrast room-temperature pulsed ODMR to self-assembled nanocrystals. Overall, our findings highlight the synthetic handles available to optically readable molecular spins and the opportunities to capitalize on chemical tunability for room-temperature quantum sensing.