Optical control of luminescence in diamond with complex nitrogen-vacancies for multi-level biolabeling
Spencer Chuang1*, Y.-P. Hsieh2, Y. F. Chen3, Y.H. Chang3, M. Hofmann3
1Graduate Institute of Applied Physics, Nation Taiwan University, 106 Taipei, Taiwan
2Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 115, Taiwan
3Department of Physics, Nation Taiwan University, Taipei 106, Taiwan
* Presenter:Spencer Chuang, email:spencer90235@msn.com
Nitrogen vacancies in diamonds have shown promise for cell tracking due to their optical stability compared to other fluorescent markers and their bio-compatibility. Moreover, the unique electronic structure that exhibits molecule-like optical transitions enable applications as in-vivo sensors for temperature and magnetic fields. Despite the large body of work on NV centers, little work has been aimed at more complex defect structures with multiple nitrogen atoms neighboring a vacancy.
We here demonstrate irreversible optical control over the fluorescent properties of extended NV defects by an all-optical method. Photoluminescence and cathodoluminescence characterization of various nano-diamond reveal the presence of complex nitrogen-vacancy assemblies containing up to 4 nitrogen atoms that generate a broad fluorescent spectrum between 400~800nm. Upon laser-irradiation, the relative contribution of N3 defects decreases in a predictable and permanent fashion over wide concentration ranges of defects and nano-diamonds. Optical detected magnetic resonance and temperature-resolved PL measurements were conducted to elucidate the charge diffusion mechanism responsible for this process.
The presented ability to vary the defect emission intensity was employed to produce non-volatile write-once read many (WORM) memory with multiple distinct memory levels. Our advance demonstrates the rich physics of complex NV defects and opens a new route for biolabeling and cytometry applications for NV diamonds.

Keywords: NV center, cell tracking, nanodiamond