ABSTRACT Fluorescent nanodiamonds (FNDs) have triggered significant interest in biochemical and chemical sensing, miniaturized optoelectronic systems, biomedical nanodevices, food packaging, nanoscale bioimaging, targeted drug delivery, photosensitizers, quantum computing, and magnetic sensing. Surface engineering had a pronounced impact on the emission, interaction, and quantum properties of NDs. This project aims to modify the optical properties of NDs through surface functionalization. NDs were synthesized via ethanol dissociation using the atmospheric‐pressure microplasma (APM) process. During the dissociation process, several parameters were kept constant, such as voltage, argon flow rate, current, and time. Meanwhile, various solvents were utilized, specifically acetone, ethanol, ethylene glycol, cyclohexene, and DI water. SAED confirmed the lonsdaleite structure. The relatively high dielectric constant, viscosity, and dipole moment of ethylene glycol formed a solid electrical double layer, resulting in ultra‐small NDs (~4.99 nm). Raman analysis confirmed the presence of mixed sp 3 /sp 2 bonding, with the highest diamond content in ethylene glycol. FTIR analysis revealed the presence of oxygen‐containing functional groups on the surface of NDs. UV–visible spectra verified absorption from oxygen functional groups. PL spectra exhibited blue (~470 nm), green (~503 nm), and yellow (~570 nm) emission from surface states. These results highlight a simple, rational surface‐engineering strategy for a broad range of FND‐based sensors, optoelectronic systems, and biomedical nanodevices.
Iqbal et al. (Thu,) studied this question.