The formation and thermodynamic stability of silicon‐vacancy (Si‐V) color centers, intensively emitting at a wavelength of 738 nm, are demonstrated for the first time in nanodiamonds less than 10 nm in size. These findings open prospects for the production of stable and efficient optical nanoemitters (single‐photon emitters) based on nanodiamond.

Recent advances within materials science and its interdisciplinary applications in biomedicine have emphasized the potential of using a single multifunctional composite material for concurrent drug delivery and biomedical imaging. Here we present a novel composite material consisting of a photoluminescent nanodiamond (ND) core with a porous silica (SiO2) shell. This novel multifunctional probe serves as an alternative nanomaterial to address the existing problems with delivery and subsequent tracing of the particles. Whereas the unique optical properties of ND allows for long-term live cell imaging and tracking of cellular processes, mesoporous silica nanoparticles (MSNs) have proven to be efficient drug carriers. The advantages of both ND and MSNs were hereby integrated in the new composite material, ND@MSN. The optical properties provided by the ND core rendered the nanocomposite suitable for microscopy imaging in fluorescence and reflectance mode, as well as super-resolution microscopy as a STED label; whereas the porous silica coating provided efficient intracellular delivery capacity, especially in surface-functionalized form. This study serves as a demonstration how this novel nanomaterial can be exploited for both bioimaging and drug delivery for future theranostic applications.

Over the last ten years, one dimensional structures, carbon nanotubes (CNTs) and carbon nanofibers, have received great attention since they are considered to be one of the main components in future nanotechnologies, in particular in the engineering of nanoscale devices. [1] Hybrid structures of CNT with other nanocarbons such as fullerenes, carbon onions or nanodiamond [2] can further extend the diversity of building units for the design of actuators, field electron emitters, novel composites and other applications. While the production of CNT and other sp 2 -bonded nanocarbons has been successfully realized by a variety of techniques, the synthesis of diamond nanowires (nanorods) of nanometer diameters -the one-dimensional sp 3 -configured analogue of CNT -turned out to be much more difficult. Using ab initio calculations, the fundamental stability of diamond nanowires (DNW) was explored depending on size and crystallographic direction, [3,4] and this object was predicted to be stable (energetically favored) at diameters ranging from 2.7 nm to 9 nm. Another prediction [5] was the instability of dehydrogenated (111) surfaces of one-dimensional nanodiamond, leading to the formation of hybrid nanorods, i.e., DNW covered by a graphitic shell, called "bucky wires". It is remarkable that hybrid nanograins called "bucky-diamond" were produced more than ten years ago, [6] whereas the "bucky-wires" never have been observed experimentally. The DNW are expected to possess unique mechanical and electronic properties, in particular: the predicted brittle fracture force and zero strain stiffness for DNW with radii greater than about 1-3 nm exceed those for CNT. [7] The elec-tronic structure of DNW has been theoretically considered by Barnard et al.;[8] they find that the band gap of diamond nanowires is narrower than that of bulk diamond, moreover it varies with the surface morphology, diameter and the orientation of the principle axis.Experimentally, diamond whiskers with a diameter as small as 60 nm have been produced by plasma etching of diamond films grown by the chemical vapor deposition (CVD) technique. [9] Aligned diamond cylinders of 300 nm diameter and 5 lm long have been grown by microwave plasma CVD (MPCVD) in a porous alumina template. [10] However, in both cases the diamond rod diameters were significantly larger than the range of interest (∼ 10 nm). Recently, aggregated diamond nanorods of 5-20 nm diameter in compact form were produced from fullerene C 60 using a high pressure-high temperature technique. [11] The material was translucent with hardness exceeding that of bulk diamond. Another approach was followed by Sun et al, [12] who produced DNW with a diameter of 4-8 nm and lengths of several hundred nanometers by a prolonged (20 hours) treatment of CNTs in a microwave hydrogen plasma. In this case, the DNWs turned out to be covered by amorphous carbon.Although synthesis of nanocrystalline diamond films by plasma assisted CVD is known for more than a decade, [13,14] only recently [15] DNWs were observed in u...

No abstract

Abstract:We report on the first observation of stimulated Raman scattering (SRS) in single crystal diamond synthesized by chemical vapor deposition (CVD). An efficiency of 45% of energy conversion from the pumping Nd 3+ :Y 3 Al 5 O 12 laser radiation to all Stokes and anti-Stokes components is achieved. This makes single crystal CVD diamond an attractive χ (3) nonlinear crystalline material as a Raman laser converter.[111] a 0 F 2gThe cubic modification of natural and synthetic diamonds crystallizes in the O 7 h -space group with 8 C atoms per unit cell