Fluorescent Microdiamonds
Fluorescent diamond particles are a chemically and mechanically robust, infinitely photostable, and biocompatible fluorophore. We provide diamond particles with nitrogen-vacancy (NV) centers with red-to-near-infrared (NIR) fluorescence, NVN centers with green fluorescence, and novel particles containing silicon-vacancy (SiV) centers emitting in NIR (HPHT diamond produced by Hyperion and distributed by Adamas). Perspective applications include exceptionally bright fluorescent labels in combination with sensing capability (via NV centers) in the fields where particles with microns sizes can be used. For example, single particles can be used for measurement of temperature and magnetic fields providing a low budget solutions in comparison with using diamond plates in a variety of applications (e.g. batteries). With their unmistakable fluorescence characteristics and chemical robustness, fluorescent diamonds can also provide protection against counterfeiters for your products. Diamond fluorescence exhibits a uniqueness that is not easily replicated and can be validated with an array of analysis techniques for assurance. Other applications include fluorescent fluid tracers, fluorescent paints, forensic, bioimaging, energy applications (e.g. photovoltaics).
Fluorescent diamond micropartices off the highest fluorescence intensity that is directly observable under UV lamp excitation (See Figure 2 and Figure 4). This is distinct from nanosized particles, where the very high scattering efficiency of the particles limits observable fluorescence without optical filtering. In addition to microdiamond particles with red-near IR fluorescence emission from NV centers, Adámas provides particles engineered to emit green fluorescence due to nitrogen-vacancy-nitrogen (NVN) centers, as well as microdiamond particles with silicon-vacancy (SiV) centers for quantum applications. The high brightness, photostability, chemical and mechical robustness, and unique spectroscopic fingerprints of fluorescent microdiamonds can be utilized in anticounterfeiting, fluid tracing, fluorescent paints, forensics, bioimaging, extreme environment sensing, and energy applications.
Technical Characteristics
Particles with NV or NVN centers: 750 nm – 150 µm
Adámas offers fluorescent microparticles with a range of sizes: 1 μm (approx. 750 nm volumetric peak via dynamic light scattering (DLS), Figure 1 and Figure 2), 3 μm, 15 μm (Figure 5), 40 μm (Figure 4) and 150 μm (Figure 4 and Figure 5). Diamond particles with red emission are enriched with NV centers, while particles with green emission are enriched with NVN centers. Typical absorption and emission profiles for NV and NVN centers are shown in Figure 3. Absorption extends into the UV region. The distinction between the negatively charged NV- and neutral NV0 centers becomes quite noticeable. The NV0 center can absorb photons all the way to ~250 nm and below, with a possibility of excitation across the band gap. Because the absorption spectra of NV0 and NV- overlap, it is possible for the NV0 center to excite the NV- center. Particles containing higher amounts of NV0 will exhibit strong fluorescence under both long-wave UV (LWUV, ~365 nm) and short-wave UV (SWUV, ~254 nm) (Figure 2 and Figure 5). High fluorescence can be observed under SWUV, where simultaneous excitation of NV- via NV0 is observed. NV- concentrations are typically on the order of 2-3 ppm based on electron paramagnetic resonance (EPR) characterization.
1 µm and larger particles are provided with primarily amphoteric surface functional groups (carboxylic acids, alcohols, etc.), but carboxylic acid enriched variants are available. Other functionalized products, such as streptavidin and biotin, are also available. Microparticles (except 1 µm and 3 µm) are typically provided as a powder/grit as they lack long term colloidal stability in solution due to their larger sizes.
Particles with SiV centers: 1 µm
High Pressure-High Temperature synthesized (HPHT) diamond particles enriched with silicon-vacancy centers are available in limited amounts. The particles are nominally 1 µm in size, and are provided in water at 0.5 mL. For additional technical details on these particles, see our publication in Advanced Optical Materials (2020): Near-Infrared Fluorescence from Silicon- and Nickel-Based Color Centers in High-Pressure High-Temperature Diamond Micro- and Nanoparticles.
