ORIGINAL RESEARCH article
Front. Quantum Sci. Technol.
Sec. Quantum Sensing and Metrology
Volume 4 - 2025 | doi: 10.3389/frqst.2025.1687810
This article is part of the Research TopicAdvanced Material Design and Post-Treatment Techniques for Enhancing Color Centers in Quantum TechnologiesView all articles
Advanced Post-Treatment Strategy for Quantum-Grade Fluorescent Nanodiamonds
Provisionally accepted
Masfer Alkahtani1*
Yahya A. Alzahrani1Ayla Hazrathosseini2
Abdulmalik M Alessa1Maabur Sow3Abdulaziz Alromaeh1Abdulrahman A. Alghihab1Faisal S. Alghannam1
Fedor Jelezko3Philip R. Hemmer2*- 1Future energy technologies institute, King Abdulaziz City for Science And Technology, Riyadh, Saudi Arabia
- 2Texas A&M University, College Station, United States
- 3Universitat Ulm, Ulm, Germany
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Fluorescent nanodiamonds (FNDs) containing nitrogen-vacancy (NV⁻) centers are promising platforms for quantum sensing and bioimaging, but their performance is often limited by surface defects, residual graphitic carbon, and ionic contamination. Here, we report a multistep surface treatment strategy combining molten potassium nitrate (KNO₃) thermal oxidation with sequential acid and alkaline cleaning to produce high-quality, quantum-grade FNDs. Molten KNO₃ etching at 580 °C enables morphological reshaping and partial oxidation, while subsequent H₂SO₄/HNO₃, NaOH, and HCl washes eliminate graphitic residues, neutralize surface charges, and remove metal ions. This protocol yields discrete, colloidally stable FNDs with enhanced photoluminescence, a high ODMR contrast of 11.5%, and extended average spin-lattice relaxation time (T₁ ≈ 2045 µs). Dynamic light scattering and ζ-potential measurements confirm excellent dispersion (~100 nm, –30 mV). The integration of chemical, morphological, and spin-performance improvements establishes a scalable route for producing FNDs suitable for high-fidelity quantum sensing and biophotonic applications.
Keywords: Fluorescent nanodiamonds, Nitrogen-vacancy centers, surface post-treatment, SpinCoherence, Quantum sensing
Received: 18 Aug 2025; Accepted: 16 Sep 2025.
Copyright: © 2025 Alkahtani, Alzahrani, Hazrathosseini, Alessa, Sow, Alromaeh, Alghihab, Alghannam, Jelezko and Hemmer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Masfer Alkahtani, mqhtani@kacst.gov.sa
Philip R. Hemmer, prhemmer@exchange.tamu.edu
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