Nanodiamonds containing silicon‐vacancy centers (SiV‐NDs) are attracting attention as promising fluorescent markers. Recently, the preparation of single‐digit‐nanometer‐sized SiV‐NDs by a detonation ...process, which can be carried out on a practical scale, has been demonstrated. However, little is known about the effect of these extremely small diamonds fabricated by a detonation process on the electronic state of the SiV centers. In the present study, SiV‐NDs prepared by the detonation process are investigated spectroscopically. It is reported that the extremely small particle size, ≈10 nm, causes an increase of the nonradiative transition probability and an enhancement of the electron–phonon coupling compared with those of typical SiV centers. Because of their electronic states, SiV‐NDs also exhibit a short luminescence lifetime (≈0.56 ns) and a large linewidth (≈14.4 nm) at room temperature. Nevertheless, the fundamental properties of the SiV center, such as the photostability, do not change, irrespective of the particle size.
Compared with typical silicon‐vacancy (SiV) centers, SiV‐center‐containing nanodiamonds (NDs) fabricated by a detonation process exhibit a shorter luminescence lifetime (0.56 ns) and a broader linewidth (0.0318 eV) at room temperature. These differences are attributed to the extremely small particle size (≈10 nm) of the NDs, which increases the nonradiative transition probability and enhances the electron–phonon coupling.
Detonation nanodiamonds have found numerous potential applications in a diverse array of fields such as biomedical imaging and drug delivery. Here, we systematically characterized non-functionalized ...and polyglycerol-functionalized detonation nanodiamond particles (DNPs) dispersed in aqueous suspensions at different ionic strengths (∼1.0 × 10
to 1.0 × 10
M) via dynamic light scattering and cryogenic transmission electron microscopy. For these colloidal suspensions, the total potential energies of interactions between a pair of DNPs were theoretically calculated using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory plus the fitting of the Boltzmann distribution to the interparticle spacing distribution of the colloidal DNPs. These investigations revealed that the non-functionalized DNPs are dispersed in aqueous media through the long-range (>10 nm) and weak (<7
) electrical double-layer repulsive interaction, while the driving force on dispersion of polyglycerol-functionalized DNPs is mostly derived from the short-range (<2 nm) and strong (∼55
) steric repulsive potential barrier generated by the polyglycerol. Moreover, our results show that the truly monodispersed and individually dispersed DNP colloids, forming no aggregates in aqueous suspensions, are available by both functionalizing DNPs by polyglycerol and increasing ionic strength of suspending media to ≳1.0 × 10
M.
Silicon vacancy (SiV) color centers in diamond have attracted widespread attention owing to their stable photoluminescence (PL) with a sharp emission band in the near-infrared region (ZPL 738 nm). ...Especially, SiV center containing single-digit nanometer-sized nanodiamonds (single-digit SiV-NDs) are desirable for various applications such as bioimaging and biosensing because of their extremely small size, comparable to many biomaterials. Therefore, several attempts have been made to fabricate the single-digit SiV-NDs. However, there are no reports on the successful fabrication of such materials in reasonable scale of production. Here, we report the successful synthesis of single-digit SiV-NDs via straightforward detonation process, which is known to have the high productivity in fabrication of single-digit NDs. Triphenylsilanol (TPS), as a silicon source, was mixed with explosives (TPS/TNT/RDX = 1/59/40 wt%) and the detonation process was carried out. The obtained single-digit NDs exhibit PL at approximately 738 nm, indicating that single-digit SiV-NDs were successfully synthesized. Moreover, we conjectured that the physics behind this achievement may be attributed to the aromatic ring of TPS under the consideration of ND formation mechanism newly built up based on the results of time-resolved optical emission measurements for the detonation reaction.
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•SiV centers in diamond are provided for various bioapplications.•SiV center-containing single-digit nanometer NDs were synthesized directly by detonation process.•Detonation with triphenylsilanol as a silicon source allowed to incorporate SiV centers into DNDs.•SiV centers in DNDs showed sharp PL emission peak centered at the ZPL = 738 nm.•Optical measurement of the detonation reaction revealed the physics behind the creation of SiV centers.
In this study, a novel approach to the explosive synthesis of titanium carbide (TiC) is discussed. Nonstoichiometric TiC
x
powder was produced via the underwater explosion of a Ti powder encapsulated ...within a spherical explosive charge. The explosion process, bubble formation, and synthesis process were visualized using high-speed camera imaging. It was concluded that synthesis occurred within the detonation gas during the first expansion/contraction cycle of the bubble, which was accompanied by a strong emission of light. The recovered powders were studied using scanning electron microscopy and X-ray diffraction. Submicron particles were generated during the explosion. An increase in the carbon content of the starting powder resulted in an increase in the carbon content of the final product. No oxide byproducts were observed within the recovered powders.
Detonation nanodiamond (DND) is the smallest class of diamond nanocrystal capable of hosting various color centers with a size akin to molecular pores. Their negatively charged nitrogen-vacancy ...center (NV−) is a versatile tool for sensing a wide range of physical and even chemical parameters at the nanoscale. The NV− is, therefore, attracting interest as the smallest quantum sensor in biological research. Nonetheless, recent NV− enhancement in DND has yet to yield sufficient fluorescence per particle, leading to efforts to incorporate other group-IV color centers into DND. An example is adding a silicon dopant to the explosive mixture to create negatively charged silicon-vacancy centers (SiV−). In this paper, we report on efficient observation (∼50% of randomly selected spots) of the characteristic optically detected magnetic resonance (ODMR) NV− signal in silicon-doped DND (Si-DND) subjected to boiling acid surface cleaning. The NV− concentration is estimated by continuous-wave electron spin resonance spectroscopy to be 0.35 ppm without the NV− enrichment process. A temperature sensitivity of 0.36K/Hz in an NV− ensemble inside an aggregate of Si-DND is achieved via the ODMR-based technique. Transmission electron microscopy survey reveals that the Si-DNDs core sizes are ∼11.2 nm, the smallest among the nanodiamond’s temperature sensitivity studies. Furthermore, temperature sensing using both SiV− (all-optical technique) and NV− (ODMR-based technique) in the same confocal volume is demonstrated, showing Si-DND’s multimodal temperature sensing capability. The results of the study thereby pave a path for multi-color and multimodal biosensors and for decoupling the detected electrical field and temperature effects on the NV− center.
Diamond nanoparticles (DNPs) are expected as splendid coating materials to give, e.g. corrosion resistance, anti-bacterial properties, and antireflection function. In this paper, we demonstrate a ...technique of electrostatic layer-by-layer deposition of DNPs onto substrate surfaces using DNP colloidal suspensions with different signs of zeta potentials alternately. The formed DNP layers are investigated in terms of film thickness, surface roughness, and homogeneity. Plus, those morphologies of DNP layers are theoretically correlated with the colloidal properties of DNP suspensions based on the electrostatic interaction potential energy between colloidal DNPs and substrate surfaces. Consequently, it turns out that the demonstrated technique enables formation of DNP thin layers with desired thickness, particle density, and surface roughness on substrate surfaces by controlling the ionic strength of colloidal DNPs.
Nanodiamonds (NDs) containing group IV-vacancy (G4V) centers—silicon-vacancy (SiV), germanium-vacancy (GeV) and tin-vacancy (SnV) centers—have shown promising potential as fluorescent markers for ...bioimaging and -sensing. However, the scale of fabrication has been limited to the laboratory scale. In this study, a detonation process was applied that enables practical scale fabrication of NDs for the direct synthesis of these G4V center-containing NDs (G4V-NDs). This detonation process for the direct synthesis of G4V-NDs employed explosives with the addition of dopant molecules with group IV atoms centered on tetraphenyl compounds. The successful synthesis of negatively charged SiV and GeV center-containing NDs (SiV- and GeV-NDs) was evidenced by photoluminescence (PL) spectra with zero-phonon lines (ZPLs) attributed to such color centers. However, as a result of the same strategy, NDs containing the SnV centers were not obtained in detectable concentrations in PL measurements. When the generated concentrations of SiV- and GeV-NDs synthesized under identical conditions were evaluated based on the number of data points that clear ZPLs were observed on the PL mappings, the SiV-NDs were found to be produced more predominantly than the GeV-NDs. The physics behind such results is explained by the difference in the reaction thermodynamics for each group IV atom.
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•Detonation process (DP) enables practical scale production of nanodiamonds (NDs).•Direct synthesis of NDs containing SiV or GeV centers was achieved by DP.•As Si or Ge sources in DP, atoms centered on tetraphenyl compounds were used.•SnV centers were not detected in NDs obtained via same scheme.•This is due to the difference in the reaction thermodynamics for each heteroatom.
Silicon-vacancy (SiV) centers in diamond are a promising candidate for all-optical nanoscale high-sensitivity thermometry because they have sufficient sensitivity to reach the subkelvin precision ...required for application to biosystems. It is expected that nanodiamonds with SiV centers can be injected into cells to measure the nanoscale local temperatures of biosystems such as organelles. However, the smallest particle size used to demonstrate thermometry using SiV centers is a few hundred nanometers. We recently developed SiV-center-containing nanodiamonds via a detonation process that is suitable for large-scale production. Here, we investigate the spectral response of SiV-center-containing detonation nanodiamonds (SiV-DNDs) to temperature. We used air-oxidized and polyglycerol-coated SiV-DNDs with a mean particle size of around 20 nm, which is the smallest size used to demonstrate thermometry using color centers in nanodiamond. We found that the zero-phonon line for SiV-DND is linearly red-shifted with increasing temperature in the range of 22.0–40.5 °C. The peak sensitivity to temperature was 0.011 ± 0.002 nm/K, which agrees with the reported high sensitivity of SiV centers in bulk diamond. A temperature sensitivity analysis revealed that SiV-DND thermometry can achieve subkelvin precision. All-optical SiV-DND thermometry will be important for investigating nanosystems such as organelles in living cells.
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