A sensor system is based on diamonds with a high density of NV centers. The description includes a) methods for producing the necessary diamonds of high NV center density, b) characteristics of such diamonds, c) sensing elements for utilizing the fluorescence radiation of such diamonds, d) sensing elements for utilizing the photocurrent of such diamonds, e) systems for evaluating these quantities, f) reduced noise systems for evaluating these systems, g) enclosures for using such systems in automatic placement equipment, g) methods for testing these systems, and h) a musical instrument as an example of an ultimate application of all these devices and methods.

Disclosed herein is a composite comprising a graphene oxide and a nanodiamond that is chemically bonded on a surface of the graphene oxide.

The present invention relates to a nano-diamond dispersion solution and a method of preparing the same. The method of preparing a nano-diamond dispersion solution comprises the following steps: providing a nano-diamond aggregation; mixing the nano-diamond aggregation with a metal hydroxide solution and stirring the mixture such that the nano-diamond aggregation is separated, to obtain a mixture solution; stabilizing the mixture solution such that the mixture solution is separated into a supernatant and precipitates; and extracting the supernatant and precipitates.

An abrasive particle having an irregular surface, wherein the surface roughness of the particle is less than about 0.95. A method for producing modified abrasive particles, including providing a plurality of abrasive particles, providing a reactive coating on said particles, heating said coated particles; and recovering modified abrasive particles.

A process for enhancing polarization of .sup.13C for subsequence MRI imaging, the process comprising providing a suspension consisting of a first plurality of particulates having NV centers and a second plurality of particulates for providing internal reflection of light with wavelength for the excitement of NV centers and .sup.13C; and applying light, magnetic field and microwave to said suspension, such that the NV centers are polarized and such that the electron spins of the VN centres are transferred to .sup.13C atoms upon the Rabi frequency of the NV centres matching the Larmor frequency of .sup.13C; wherein the particulates of the second plurality reflect and transmit the light through the suspension such that said light is distributed through said suspension.

Provided are: a polyglycerin-chain surface-modified nanodiamond having excellent dispersibility in a low-polarity solvent; and a method of producing the polyglycerin-chain surface-modified nanodiamond. A surface-modified nanodiamond 1 includes a nanodiamond particle 2 and a surface-modifying group 3 that surface-modifies the nanodiamond particle 2, the surface-modifying group 3 having a polyglycerin chain in which a hydrogen atom of at least some of the hydroxyl groups in the polyglycerin chain is substituted by a monovalent organic group.

Provided are: a polyglycerin-chain surface-modified nanodiamond having excellent dispersibility in a low-polarity solvent; and a method of producing the polyglycerin-chain surface-modified nanodiamond. A surface-modified nanodiamond 1 includes a nanodiamond particle 2 and a surface-modifying group 3 that surface-modifies the nanodiamond particle 2, the surface-modifying group 3 having a polyglycerin chain in which a hydrogen atom of at least some of the hydroxyl groups in the polyglycerin chain is substituted by a monovalent organic group.

The present invention provides a fluorescent diamond containing an MV center emitting fluorescence at a concentration of 1×10.sup.14/cm.sup.3 or higher, where M represents a metal or metalloid, and V represents a vacancy.

The present invention provides a fluorescent diamond containing an MV center emitting fluorescence at a concentration of 1×10.sup.14/cm.sup.3 or higher, where M represents a metal or metalloid, and V represents a vacancy.

A method of controlled production of luminescent diamond particles exhibiting luminescence in selected specific spectral ranges is provided. The method comprises taking diamond particles containing dopant atoms in the diamond core, irradiating the particles with high energy radiation, and annealing the irradiated diamond particles at a target temperature in the temperature range of about 1400° C.-2200° C. to form luminescent diamond particles where the specific spectral range of luminescence is controlled by the target temperature of the annealing process, the irradiation dose, and the type of dopant atoms. Duration of the annealing and the temperature ramp up and ramp down times should be short enough to minimize or prevent significant graphitization of the particles. Duration of the temperature ramp up time should be short enough to minimize formation of color centers that might form at temperatures below the target temperature.