title: Creation of high density ensembles of nitrogen-vacancy centers in nitrogen-rich type Ib nanodiamonds.
abstract: This work explores the possibility of increasing the density of negatively charged nitrogen-vacancy centers ([NV(-)]) in nanodiamonds using nitrogen-rich type Ib diamond powders as the starting material. The nanodiamonds (10-100 nm in diameter) were prepared by ball milling of microdiamonds, in which the density of neutral and atomically dispersed nitrogen atoms ([N(0)]) was measured by diffuse reflectance infrared Fourier transform spectroscopy. A systematic measurement of the fluorescence intensities and lifetimes of the crushed monocrystalline diamonds as a function of [N(0)] indicated that [NV(-)] increases nearly linearly with [N(0)] at 100-200 ppm. The trend, however, failed to continue for nanodiamonds with higher [N(0)] (up to 390 ppm) but poorer crystallinity. We attribute the result to a combined effect of fluorescence quenching as well as the lower conversion efficiency of vacancies to NV(-) due to the presence of more impurities and defects in these as-grown diamond crystallites. The principles and practice of fabricating brighter and smaller fluorescent nanodiamonds are discussed.
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
authors.forename: Long-Jyun
authors.initials: LJ
authors.lastname: Su
authors.forename: Chia-Yi
authors.initials: CY
authors.lastname: Fang
authors.forename: Yu-Tang
authors.initials: YT
authors.lastname: Chang
authors.forename: Kuan-Ming
authors.initials: KM
authors.lastname: Chen
authors.forename: Yueh-Chung
authors.initials: YC
authors.lastname: Yu
authors.forename: Jui-Hung
authors.initials: JH
authors.lastname: Hsu
authors.forename: Huan-Cheng
authors.initials: HC
authors.lastname: Chang
mesh_terms: D018130:Diamond / Q000737:chemistry*; D005453:Fluorescence; D058612:Nanodiamonds / Q000737:chemistry*; D050997:Nanomedicine; D009584:Nitrogen / Q000737:chemistry*; D011208:Powders; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D058612:Nanodiamonds; D011208:Powders; D018130:Diamond; D009584:Nitrogen