Nanoparticles and nanomaterials are revolutionizing medicine by offering diverse tools for diagnosis and therapy, including devices, contrast agents, drug delivery systems, adjuvants, therapeutics, and theragnostic agents. Realizing full applied potential requires a deep understanding of the interactions of nano dimensional objects with biological cells. In this study, we investigate interaction of single-crystal diamond nanoneedles (SCDNNs) containing silicon vacancy (SiV-) color centers with biological substances. Four batches of the diamond needles with sizes ranging between 200 nm and 1300 nm and their water suspensions were used in these studies. The human lung fibroblast cells were used for the proof-of-concept demonstration. Employing micro-photoluminescence (PL) mapping, confocal microscopy, and lactate dehydrogenase (LDH) viability tests, we evaluated the cellular response to the SCDNNs. Intriguingly, our investigation with PL spectroscopy revealed that the cells and SCDNNs can coexist together with approved efficient registration of SiV-centers presence. Notably, LDH release remained minimal in cells exposed to optimally sized SCDNNs, suggesting a small number of lysed cells, and indicating non-cytotoxicity in concentrations of 2-32µg ml-1. The evidence obtained highlights the potential of SCDNNs for extra- or/and intracellular drug delivery when the surface of the needle is modified. In addition, fluorescent defects in the SCDNNs can be used for bioimaging as well as optical and quantum sensing.

In this study we demonstrate formation of all-carbon heterostructures induced by field electron emission from diamond needle-shaped crystallites with nanoscale tips. We show that at certain experimental conditions a carbon nanoprotrusion can be formed at the apex of a diamond emitter. Staircase-like current-voltage curves observed for such emitters indicated the presence of the Coulomb blockade effect in the self-assembled all-carbon heterostructures. The mechanism of nanoprotrusion formation via the field-induced surface diffusion of carbon atoms is revealed by observing the structural transformation of the emitter material using transmission electron microscopy. We also explore how the properties of the formed heterostructures evolve with the field emission current, and show that the characteristic size of the formed nanoprotrusion depends on the dimensions of the diamond nanotip. The developed approach offers a way to reproducible fabrication of heterostructured emitters which can be applied as coherent single-electron sources in vacuum nanoelectronics and electron quantum optics.

Direct current plasma enhanced chemical vapor deposition (CVD) was employed to create polycrystalline diamond films from CH4/H2 gaseous mixture at 98 mbar pressure and various substrate temperatures between 720 degrees C and 960 degrees C. The Si chips with patterns of periodic masked and open seeded zones were used as substrates. The mask free seeded areas evolved into polycrystalline diamond films after CVD process. The diamond crystallites of the films featured single crystal ordering individually with distinct cubic (100) or octahedral (111) facets on the film surfaces. Notably, specific growth conditions were determined for obtaining diamond films composed of the crystallites of nanometre and micrometre scale. These conditions are differing from those observed for non-pattern-prepared Si substrates. The nano-crystalline diamonds emerged within the 4.5-5 A current range, with growth conditions involving 3% CH4/H2 mixture at 98 mbar. The micro-crystalline diamonds (MCDs) predominantly characterized by well-developed rectangular (100) crystal faces on the film surface were successfully grown with current settings of 5.5-6 A, under 3% CH4/H2 mixture at 98 mbar. Furthermore, MCDs characterized by entirely crystalline (111) diamond faces forming CVD film surface were attained within a growth parameter range of 4.5-5.8 A, employing 3% CH4/H2 mixture for certain samples, or alternatively, utilizing 5 A with a 1.5% CH4/H2 mixture for others. Upon thorough evaluation, it was established that SiO2, TiO2, and Cr masks are well-suited materials for the planar patterning of both nano- and micro-crystalline diamond films, and the bottom-up approach can pave the way for the production of diamond planar structures through CVD, facilitated by electron beam lithography (EBL).

Unique properties possessed by transition metal dichalcogenides (TMDs) attract much attention in terms of investigation of their formation and dependence of their characteristics on the production process parameters. Here, we investigate the formation of TMD films during chemical vapor deposition (CVD) in a mixture of thermally activated gaseous H2S and vaporized transition metals. Our observations of changes in morphology, Raman spectra, and photoluminescence (PL) properties in combination within situmeasurements of the electrical conductivity of the deposits formed at various precursor concentrations and CVD durations are evidence of existence of particular stages in the TMD material formation. Gradual transformation of PL spectra from trion to exciton type is detected for different stages of the material formation. The obtained results and proposed methods provide tailoring of TMD film characteristics necessary for particular applications like photodetectors, photocatalysts, and gas sensors.

The presented study investigates the impact of continuous laser irradiation in the visible range on the field emission properties of diamond needle-like micro-sized crystallites with a nanometer tip radius. The measurements were carried out in a vacuum diode configuration with a flat metal anode using DC voltage source. It was found that the field emission current increased under illumination, showing a direct correlation with the radiation power. At a maximum power density of about 400 W/cm2 the relative increase in current under the action of laser irradiation was 13%. The relative increase in current is determined by the parameters of the dark current-voltage characteristic and reaches its maximum value in the region corresponding to the minimum increase in dark current with voltage. It is shown that the most likely mechanism for the increase in current is a change in the electrical resistance of the diamond microneedle as a result of absorption of laser radiation in the presence of electron levels located in the band gap of the diamond associated with impurities or structural defects in the near surface layer of the diamond microneedle.

Due to its outstanding mechanical characteristics, diamond is an ideal material for use in micro- and nano-electromechanical systems. In this paper, we report on the investigation of vibrational properties of singly clamped needlelike diamond microcrystallites with nanoscale tips. The single-crystal diamond needles were produced by selective oxidation of polycrystalline films grown using chemical vapor deposition. The study of resonant oscillations driven by the AC voltage indicated that the elastic modulus of such diamond needles is close to that of bulk single crystal diamond. A self-oscillation regime induced by the DC voltage during field emission from the apex of a diamond needle is also demonstrated. It is shown that this regime can be used for efficient DC–AC conversion in microdevices. The high structural quality of diamond needles, their remarkable mechanical properties, and the relative ease of their mass fabrication make them promising candidates for application in various electromechanical systems, field-emission devices, and scanning probe techniques.

Herein, the efficiency of generation of unipolar photocurrent pulses under action of obliquely incident nanosecond laser pulses is studied in carbon nanowall (CNW) films on silicon substrate depending on the direction of the wave vector and polarization of the laser radiation. The films consist of flake‐like graphite crystallites of nanometer thickness. Each of the crystallites comprises stacked graphene atomic sheets oriented mostly perpendicular to the substrate surface with random orientation in other directions. The angular and polarization dependencies of the longitudinal and transverse photocurrents at wavelengths of 266, 354.7, 532, and 1064 nm are measured. The longitudinal and transverse photocurrents are odd functions of the incidence angle, and, for a given angle of incidence, they are even and odd functions of the polarization azimuth, respectively. It is noteworthy that with the decrease in exciting radiation wavelength, the conversion coefficients of laser pulse power into longitudinal and transverse photocurrents increase and decrease, respectively. At wavelength of 266 nm, the transverse photocurrent changes its polarity, and the longitudinal photocurrent generated by s ‐polarized radiation exceeds the p ‐polarized radiation photocurrent. The obtained results are explained by morphology peculiarities of the CNW films and the surface photogalvanic effect photocurrent generation.

Production and characterization of molybdenum disulfide (MoS2) and other transition metal dichalcogenide materials attract significant attention of scientific community due to pronounced two‐dimensional character of their electronic properties. Herein, MoS2 synthesis by chemical vapor deposition with gaseous hydrogen sulfide (H2S) containing thermally evaporated molybdenum (Mo) is presented. The films deposited onto silicon (Si) substrate consist of flake‐like crystallites of nanometer thickness assembled of parallel atomic layers oriented predominantly along a normal to the substrate surface. The dependence of film morphology on deposition time, substrate temperature, and precursor composition in gaseous phase is investigated. The Raman spectroscopy and electron microscopy analysis reveal the presence of mono‐ and bilayered structures in the film. Photoluminescence (PL) efficiency of the films is found to be increased in comparison with the monolayer MoS2 crystallites. The high PL efficiency in combination with the high spatial uniformity of the film materials makes them prospective for application in electronic and photonic industry.

Monitoring of tiny intracell temperature variations is of high importance to understand the mechanisms of exothermic/endothermic processes inside the living cells. Small shifts in thermal balance may drastically influence cell functioning and induce pathological conditions. By using biocompatible diamond single‐crystal microneedles enriched with nitrogen‐vacancy (NV)/silicon‐vacancy (SiV) color centers, this study demonstrates all‐optical in vitro temperature monitoring in the physiologically significant range (25–55 °C). Zero‐phonon line (ZPL) of SiV centers belonging to the “therapeutic window” is used to improve measurement precision via suppression of the tissue autofluorescence. The simultaneous detection of the NV and SiV fluorescence enables two‐band visualization of the living cells combined with the temperature sensing. This study demonstrates experimentally that temperature can be measured by lifetime, full‐width at half maximum, and peak position of SiV ZPL, while accuracy can be further improved by normalizing the photoluminescence (PL) ZPL peak intensity on the PL signal measured at the wavelength where it is temperature independent. According to performed numerical simulations diamond microneedles enable real‐time temperature measurements because their characteristic heating time is less than 10 ns. The results open a way toward accurate, noninvasive, precise, and real‐time monitoring of temperature variations accompanying intracellular biochemical reactions and processes on the single‐cell level.

Improving the thruster efficiency is a crucial challenge for the development of space electric propulsion systems, especially advanced air-breathing thrusters utilizing the surrounding rarefied atmosphere as fuel. A significant reduction in thruster power consumption can be achieved by using field emission (FE) cathodes that do not require heating and have the highest energy efficiency. In this work, we study FE from nano-graphite thin films, consisting of carbon nanostructures with a high aspect ratio, and demonstrate their suitability for use in the space electric propulsion systems. The films shown appropriate FE characteristics in a wide range of gas pressures at high current loads in constant and pulsed operation modes. Based on the obtained experimental results, nano-graphite cathodes were employed for the design of an electron gun with increased reliability and minimized energy losses associated with electron extraction. The possibility of using such a gun in a specific air-breathing satellite operating in low Earth orbits is demonstrated.

Surface graphitization as a result of Joule heating by a field-emission (FE) current is revealed for needlelike diamond nanotips. The apex temperature and electrical resistance of the diamond needles during FE were measured by electron spectroscopy. Transmission electron microscopy indicated that the diamond structure in the near-surface layer was transformed into well-ordered graphene layers after FE with currents of up to 30 μA. The resulting structure can be viewed as a multi-walled carbon nanotube (MWCNT) having a diamond core. Thus, the observed FE behavior exhibited by the graphitized diamond needles is qualitatively similar to that of MWCNTs. On the other hand, due to its outstanding thermal conductivity, the diamond core ensures an efficient Joule heat dissipation, which provides better emission stability and higher currents, up to at least 225 μA. It makes these graphitized diamond needles promising candidates for high-brightness point electron sources required for various applications, e.g., in electron microscopy or scanning electron lithography.

Single-crystal diamond needles in the form of micrometer-scale sharp pyramids were produced using a combination of chemical vapor deposition and thermal oxidation processes. These diamond needles with atomic-sized fluorescent defects (color centers) attract great interest for practical applications as a platform for creation of optical quantum sensing probes and optical quantum communication elements. Particular color centers localization providing suitable luminescence characteristics is required for these applications. Here we report about formation of nitrogen-vacancy (NV), silicon-vacancy (SiV) and germanium-vacancy (GeV) centers in the singlecrystal diamond needles during direct current discharge plasma enhanced chemical vapor deposition (PE CVD). Luminescent characteristics of the needles were observed by confocal photoluminescence mapping. Analysis of experimental results allows us proposing possible mechanisms of impurities introduction into the crystal lattice during needles growth. These mechanisms include gas decomposition and etching of substrate material during CVD. The proposed mechanisms were approved by realization of CVD process protocols resulting in controllable formation of NV, SiV and GeV centers in single-crystal diamond needles including formation of thin NV- and SiVenriched layers by tuning deposition process parameters. The proposed experimental approaches in combination with revealed mechanisms for introduction of favorable impurities make single-crystal diamond needles promising candidates for scanning quantum sensing, quantum communication and hyperpolarization experiments.

Molybdenum disulfide is a crystalline material which attracts considerable attention due to explicit two-dimensional cha- racter of its electronic properties. To obtain MoS2 films thermally evaporated molybdenum and gaseous H2S were used as precursors in this work. As a result of chemical reaction of these precursors films consisting of flake-like of nanometer thickness assembled from parallel atomic layers with predominantly perpendicular (with respect to substrate surface) orientation were deposited on the surface of Si substrate. In this work we investigate the dependence of film morphology on deposition time, substrate temperature and concentration of precursors in gaseous phase. Presence of mono- and bi-layered structures in the film was revealed using Raman spectroscopy and electron microscopy. Dependence of photoluminescence properties on size of crystallites in produced films was also studied.

Molybdenum disulfide is a crystalline material which attracts considerable attention due to explicit two-dimensional character of its electronic properties. To obtain MoS 2 films thermally evaporated molybdenum and gaseous H 2 S were used as precursors in this work. As a result of chemical reaction of these precursors films consisting of flake-like of nanometer thickness assembled from parallel atomic layers with predominantly perpendicular (with respect to substrate surface) orientation were deposited on the surface of Si substrate. In this work we investigate the dependence of film morphology on deposition time, substrate temperature and concentration of precursors in gaseous phase. Presence of mono- and bi-layered structures in the film was revealed using Raman spectroscopy and electron microscopy. Dependence of photoluminescence properties on size of crystallites in produced films was also studied. Keywords: 2D materials, transition metal dichalcogenides, flakes, monolayers, mesoporous films.

In this work thin film coatings based on WS 2 , MoS 2 , MoO 2 and their composites were synthesized, morphological and structural properties of deposited coatings were studied. Chemical vapor deposition with heated MoO 3 , WO 3 , S powder as precursors was used. Dependence of structural and morphological properties, chemical composition of deposited films on parameters of synthesis was defined. Films of vertically aligned 10 nm thick plate crystals consisting both of pure MoO 2 and MoO 2 covered with thin MoS 2 layer were obtained. Formation of polycrystalline films of regular triangular shaped WS 2 and uniform continuous 20 nm thick WS 2 films with covering area of 2x2 mm has also been observed. In this work we also report about synthesis of films consisting of regular triangular shaped WS 2 crystals and MoS 2 irregularly shaped crystals overlapping each other. Keywords: 2D materials, transition metal dichalcogenides, heterostructures, CVD, AFM.

An automated device is described that makes it possible to obtain maps of the spatial distribution of the composition and intensity of the components of the optical emission spectra of an activated gaseous medium, as well as to conduct thermometry using machine-learning methods based on a quick comparison of calculated and experimentally recorded radiation spectra. The interpreted Python programming language with a set of specialized libraries was used both to automate the registration of spectra and to analyze them using machine-learning methods. The apparatus was tested based on the example of a methane-hydrogen gas medium activated by a direct current discharge in an apparatus for the plasma–chemical deposition of carbon nanomaterials. The software of the automated apparatus allows one to supplement the measurement procedure by including additional software modules without changing the program code of the main control program.

In this work thin film coatings based on WS2, MoS2, MoO2 and their composites were synthesized, morphological and structural properties of deposited coatings were studied. Chemical vapor deposition with heated MoO3, WO3, S powder as precursors was used. Dependence of structural and morphological properties, chemical composition of deposited films on parameters of synthesis was defined. Films of vertically aligned 10 nm thick plate crystals consisting both of pure MoO2 and MoO2 covered with thin MoS2 layer were obtained. Formation of polycrystalline films of regular triangular shaped WS2 and uniform continuous 20 nm thick WS2 films with covering area of 2x2mm has also been observed. In this work we also report about synthesis of films consisting of regular triangular shaped WS2 crystals and MoS2 irregularly shaped crystals overlapping each other.