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Nanodiamonds for Bioimaging and Therapeutic Applications
Published in Yubing Xie, The Nanobiotechnology Handbook, 2012
V. Vaijayanthimala, Yuen Yung Hui, Huan-Cheng Chang
The negatively charged nitrogen-vacancy center, (N–V)−, is perhaps the best characterized color center in diamond (Santori et al. 2010, Aharonovich et al. 2011b). It is a point defect consisting of a substitutional nitrogen atom adjacent to a carbon atom vacancy with C3v symmetry (Figure 25.1). The center exhibits a zero-phonon line (ZPL) at 638 nm, accompanied with a broad phonon sideband peaking at —560 nm (Davies and Hamer 1976). The absorption cross section of the center at 532 nm is 0.95 × 10−16 cm2 (Chapman and Plakhotnik 2011). When excited by green yellow light, the center emits far-red fluorescence at —700 nm with a near-unity quantum yield (Rand 1994). Moreover, the fluorescence is perfectly stable, showing no sign of photoblinking and photobleaching even under continuous high-power laser excitation at room temperature (Gruber et al. 1997). Because of these outstanding features, the (N–V)− center has been employed as a single-photon source for quantum information application (Aharonovich 2011a). Fu et al. have performed pho-tostability tests for the (N–V)− centers in FNDs (Fu et al. 2007). The fluorescence intensities of the individual FND particles of size of 35 and 100 nm stay nearly the same over a time period of 300 s (Figure 25.2). In contrast, organic dye molecules such as Alexa Fluor 546 photobleach in 12 s.
Tuning diamond electronic properties for functional device applications
Published in Functional Diamond, 2022
Anliang Lu, Limin Yang, Chaoqun Dang, Heyi Wang, Yang Zhang, Xiaocui Li, Hongti Zhang, Yang Lu
As a nanoscale sensor, NV center is sensitive to the surrounding environment (magnetic, electrical, and strain field, etc.) [14,143,144]. It is possible to modulate the properties of NV center by mechanical strain and researchers have obtained some interesting results. S. Bennett et al. [145] proposed a strategy to realize phonon-induced spin-spin interactions by coupling them via strain introduced by vibrational mode of a diamond mechanical nanoresonator. The spin dephasing and relaxation are depressed significantly by generating substantial squeezed states of a spin ensemble. P. Ovartchaiyapong et al. [14] fabricated diamond cantilever with an embedded nitrogen-vacancy center. As shown in Figure 9(c), the couple of mechanical strain and the spin of the NV center is realized by the mechanical motion of the diamond cantilever. The NV center behaved as an atomic-scale sensor and the spin-based strain imaging reached a strain sensitivity of 3*10−6 strain Hz−1/2. A. Barfuss et al. [146] presented a new approach to coherently manipulate a single electronic spin via internal strain. Time-varying stain was applied on a diamond cantilever to generate long-lasting, coherent oscillations of a NV center spin. The phonon-dressed states were observed by direct spectroscopy and the spin coherence time of the NV center was enhanced significantly by the continuous strain.
Optical defects and their depth penetration in 200 keV electron irradiated IIa diamond
Published in Radiation Effects and Defects in Solids, 2020
Ruiang Guo, Kaiyue Wang, Senchuan Ding, Hongxing Wang
Figure 2 presents the PL spectra of the colorless diamond involved before and after irradiation which are obtained at ∼80 K with 532 nm laser excitation. The sharp peak at 2.164 eV with a linewidth of 0.63 meV is the Raman that is an indication of the high quality of crystals (18). The 1.945 eV line is associated with the negatively charged nitrogen vacancy center in diamond and usually marketed as NV- center (19). After 200 keV electron irradiation, the NV- luminescence decreases. There are also three new zero phonon lines (ZPLs) observed in Figure 2 including 1.673, 2.091 and 2.095 eV. The 1.673 eV line is well-understood to be an isolated neutral vacancy in diamond and named as GR1 center (20). However, such emissions at 2.091 and 2.095 eV have not been well understood yet.