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We observe cavity-enhanced ensemble fluorescence of nitrogen-vacancy centers in diamond, showing Purcell-enhancement of the Zero Phonon Line (ZPL). The emission features temporal bunching of ZPL photons, indicating collective emission that can be attributed to superfluorescence.

Certain aspects before and during the fabrication of single-crystal diamond (SCD) membranes are highlighted, which are decisive to obtain high-quality membranes with low surface roughness values around 0.2 nm on a small area scale. In addition to the requirements for the starting material, including a high planarity and a moderate surface roughness, the importance of cleaning processes to minimize particles and impurities before and during the structuring is emphasized. With the help of a planarization procedure, consisting of a combination of different Ar/Cl$_2$ recipes with low etch rates, surface defects like grooves due to polishing are minimized and smooth surfaces are acquired. Severe micromasking can be prevented by the application of a cyclic Ar/Cl$_2$ + O$_2$ recipe, allowing finally the fabrication of defect-minimized and planarized SCD membranes in the thickness range between few microns and a few hundred nanometers. The high quality of the structured SCD membranes is evidenced with a morphological as well as an optical characterization via fiber-based microcavity measurements.

We introduce and demonstrate a new approach for nitrogen-vacancy (NV) patterning in diamond, achieving a deterministic, nanometer-thin, and dense delta-doped layer of negatively charged NV centers in diamond. We employed a pure nitridation stage using microwave plasma and a subsequent in situ diamond overgrowth. We present the highest reported nitrogen concentration in a delta-doped layer (1.8 × 1020 cm-3) while maintaining the pristine diamond crystal quality. This result combined with the large optically detected magnetic resonance contrast can pave the way toward highly sensitive NV-based magnetometers. We further employed this delta-doping technique on high-quality fabricated diamond nanostructures for realizing a topographic NV patterning in order to enhance the sensing and hyperpolarization capabilities of NV-based devices.

Ultrananocrystalline diamond (UNCD) is a promising and - so far - relatively unexploited material for biocatalytic applications. In this study, UNCD films, deposited on silicon wafers by microwave plasma-assisted chemical vapor deposition, were investigated as supports for immobilization of the enzyme lipase B from Candida antarctica (CalB). The motivation for this work was the potential of utilization of the resulting biomaterials for the fabrication of flow bioreactors, harnessing both the benefits of the UNCD and the biocatalysts. Prior to immobilization, the UNCD surfaces were structured by reactive ion etching with a randomly distributed gold nanodroplet mask that was applied on top of the UNCD films, in order to increase the area for interaction with the enzyme. Furthermore, structured UNCD films were subjected to modification by UV/ozone treatment or trifluoromethane plasma which rendered the surfaces oxygen-terminated and hydrophilic or fluorine-terminated and hydrophobic, respectively. Two established coupling strategies, based on carbodiimide and oxalyl chloride chemistry, were investigated for covalent immobilization of CalB on structured oxygen-terminated surfaces. However, non-covalent immobilization on fluorine- and as-grown hydrogen-terminated surfaces, mediated by physical adsorption of the enzyme, appeared to be more efficient. Moreover, the data strongly suggested that the chemical nature of the termination and the hydrophobicity of the surface influence the substrate selectivity of the enzyme. Non-covalently immobilized CalB on strongly hydrophobic fluorine-terminated surfaces showed a ~5.5-fold higher preference for the short-chain substrate p-nitrophenyl butyrate over the medium-chain ester p-nitrophenyl laurate, whereas on hydrophilic O-terminated surfaces this selectivity was only ~1.9-fold. Moderately hydrophobic H-terminated surfaces conferred a selectivity ratio of ~3.5, which is in between the two former values and therefore in line with the hypothesized dependence of the substrate selectivity on the hydrophobicity of the surface material. These primary results can help on the optimization of the design of immobilized biocatalysts on UNCD surfaces to produce columns for flow bioreactors. Prime novelty Nanostructured modified ultrananocrystalline diamond (UNCD) surfaces were studied as immobilization support for lipases. The physical adsorption of lipase CalB was more efficient on hydrophobic F- or H-terminated surfaces than the two covalent coupling approaches on hydrophilic O-terminated UNCD. Furthermore, the chemical nature of the surface termination had an impact on the substrate selectivity by catalyzed hydrolysis.

Successful osseointegration, i.e. the fully functional connection of patient's bone and artificial implant depends on the response of the cells to the direct contact with the surface of the implant. The surface properties of the implant which trigger cell responses leading to its integration into the surrounding bone can be tailored by surface modifications or coating with thin layers. One potential material for such applications is ultrananocrystalline diamond (UNCD). It combines the exceptional mechanical properties of diamond with good biocompatibility and possibility of coating as thin uniform films on different substrates of biological interest. In the current work we firstly deposited UNCD films on titanium-coated substrates and applied oxygen or ammonia plasma to modify their surface properties. The as-grown and modified UNCD exhibited relatively smooth surfaces with topography dominated by rounded features. The modifications induced oxygen- or amino-terminated surfaces with increased hydrophilicity. In addition, the UNCD coatings exhibited very low coefficient of friction when diamond was used as a counterpart. As-grown and modified UNCD samples were applied to study the responses of human osteoblast MG63 cells triggered by surfaces with various terminations assessed by proteomic analysis. The results revealed that the coating of Ti with UNCD as well as the plasma modifications resulting in O- or NH2-terminated UNCD induced upregulation of proteins specific for cytoskeleton, cell membrane, and extracellular matrix (ECM) involved in the cell-ECM-surface interactions. Proteins from each of these groups, namely, vimentin, cadherin and fibronectin were further studied immunocytochemically and the results confirmed their increased abundance leading to improved cell-to-surface adhesion and cell-to-cell interactions. These findings demonstrate the potential of implant coating with UNCD and its surface modifications for better osseointegration and bone formation.

The surface patterning of a biomaterial, i.e. placing areas with different surface chemistries next to each other is an important step for various biomedical and biotechnological applications, e.g. in biosensor technology, drug screening or tissue engineering. In the current work we investigated the patterning of the surface termination of ultrananocrystalline diamond (UNCD) films prepared by microwave plasma chemical vapor deposition. In order to achieve a high wettability contrast in the neighboring areas O- and F-terminations were selected. The sequence of the modifications and the feasibility of different masking techniques were tested in advance. Based on the achieved results the following process of surface patterning was applied. Initially the whole UNCD surface was modified by UV/O3 treatment rendering the surface O-terminated and strongly hydrophilic (contact angle against water of 11°). The partial masking of this surface before the second modification was achieved with a gold hard mask photolithographically structured and wet etched in form of a grid. After the second modification with CHF3 plasma which provided F-termination and hydrophobic character of the surface (contact angle > 110°), the gold layer was removed. The results of the patterning of the surface termination were visualized by scanning electron microscopy revealing different contrasts of the areas with different terminations. Finally, human SH-SY5Y neuroblastoma cells were plated on the patterned UNCD surfaces and they exhibited preferential attachment and growth on the hydrophilic grid.

Diamond attracts an ever-increasing scientific interest not only due to its outstanding properties, but also as host material for the so-called color centers. In particular, the nitrogen-vacancy (NV) center is a promising candidate for applications in quantum sensing on a nanoscale. Incorporating such centers in sharp diamond tips, allows the fabrication of a controllable sensor for magnetic and electric fields. In this regard, we present two different ways to fabricate diamond atomic force microscope (AFM) probes. One approach is based on a bottom-up method, first structuring a silicon substrate by photolithography and anisotropic wet etching and subsequently depositing a nanocrystalline diamond (NCD) film onto the pre-patterned silicon substrate. The second approach is based on electron beam lithography (EBL) and reactive ion etching (RIE), which is also applicable to monocrystalline diamond (MCD). To this end we show our first results in fabricating NV-containing MCD tips by He+ ion implantation and annealing. We demonstrate the fabrication of bottom-up NCD probes with tip radii in the range of ca. 25 nm, and top-down fabricated NCD AFM probes with tip radii even below 10 nm.

The negatively charged silicon-vacancy center (SiV) in diamond is a potential high-quality single-photon source for quantum information processing and quantum electrodynamics applications[1]. The dipole moment of the SiV is aligned predominantly along its symmetry axis which connects the interstitial silicon atom and the two adjacent vacancies with 4 possible -orientations. Since the SiV addressing is done optically the demand for efficient excitation and optical out-coupling is essential for realizing high-quality single-photon sources. In addition to relatively low extraction efficiency when embedded in bulk diamond, attributed to total internal reflection, in a -oriented diamond, which is commonly used, each SiV possesses a dominant dipole component aligned normal to the diamond-air interface. Thus, resulting in a poor optical out-coupling since a dipole radiates primarily into the plane orthogonal to its axis.

Ultrananocrystalline diamond films have been subjected to CHF3 and SF6 rf plasmas in order to achieve a fluorine terminated surface. Major parameter varied in this study was besides the nature of the process gas the exposure time. The treated surfaces have been investigated by contact angle and atomic force microscopy measurements; X-ray photoelectron spectroscopy has been used to determine the surface composition and to get insight into the bonding environments of the treated surfaces. Both plasma treatments lead to similar results. The surfaces are fluorinated by fluorine containing groups, namely CF, CF2, and CF3, with F concentrations of about 20%. This leads to high contact angles of 95–110°; the surfaces are slightly etched and became somewhat smoother. Nevertheless, there are distinct differences between the surface obtained by the CHF3 and SF6 treatments, respectively, the nature of which will be discussed in this paper, together with the underlaying mechanisms.

Phthalocyanine (Pc) derivatives containing different central metal atoms (Mn, Cu, Ti) and different peripheral chains were synthesized and comprehensively characterized. Their interaction with nanocrystalline diamond (NCD) films, as-grown by hot-filament chemical vapor deposition or after their modification with oxygen plasma to exchange the hydrogen termination with oxygen-containing groups, was studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The elemental composition as determined by XPS showed that the Pc were grafted on both as-grown and O-terminated NCD. Mn, Cu and Ti were detected together with N stemming from the Pc ring and S in case of the Ti-Pc from the peripheral ligands. The results for the elemental surface composition and the detailed study of the N 1s, S 2p and O 1s core spectra revealed that Ti-Pc grafted better on as-grown NCD but Cu-Pc and Mn-Pc on O-terminated films. Samples of Mn-Pc on as-grown and O-terminated NCD were further investigated by NEXAFS spectroscopy. The results showed ordering of the grafted molecules, laying flat on the H-terminated NCD surface while only the macrocycles were oriented parallel to the O-terminated surface with the peripheral chains perpendicular to it.

Diamond is a promising material for a number of bio-applications, including the fabrication of platforms for attachment and investigation of neurons and of neuroprostheses, such as retinal implants. In the current work ultrananocrystalline diamond (UNCD) films were deposited by microwave plasma chemical vapor deposition, modified by UV/O-3 treatment or NH3 plasma, and comprehensively characterized with respect to their bulk and surface properties, such as crystallinity, topography, composition and chemical bonding nature. The interactions of insect circadian pacemaker neurons with UNCD surfaces with H-, O- and NH2-terminations were investigated with respect to cell density and viability. The fast and strong attachment achieved without application of adhesion proteins allowed for advantageous modification of dispersion protocols for the preparation of primary cell cultures. Centrifugation steps, which are employed for pelletizing dispersed cells to separate them from dispersing enzymes, easily damage neurons. Now centrifugation can be avoided since dispersed neurons quickly and strongly attach to the UNCD surfaces. Enzyme solutions can be easily washed off without losing many of the dispersed cells. No adverse effects on the cell viability and physiological responses were observed as revealed by calcium imaging. Furthermore, the enhanced attachment of the neurons, especially on the modified UNCD surfaces, was especially advantageous for the immunocytochemical procedures with the cell cultures. The cell losses during washing steps were significantly reduced by one order of magnitude in comparison to controls. In addition, the integration of a titanium grid structure under the UNCD films allowed for individual assignment of physiologically characterized neurons to immunocytochemically stained cells. Thus, employing UNCD surfaces free of foreign proteins improves cell culture protocols and immunocytochemistry with cultured cells. The fast and strong attachment of neurons was attributed to a favorable combination of topography, surface chemistry and wettability. (C) 2016 Elsevier B.V. All rights reserved.

Fly ash (FA) from lignite coal combusted in different Thermal Power Plants (TPPs) was used for the synthesis of zeolites (FAZs) of the Na-X type by alkaline activation via three laboratory procedures. FAZs were characterized with respect to their morphology, phase composition and surface properties, which predetermine their suitability for applications as catalysts and adsorbents. FAZs were subsequently modified with metal oxides (CuO) to improve their catalytic properties. The catalytic activity of non-modified and CuO-modified FAZs in the total oxidation of volatile organic compounds was investigated. FAZs were studied for their potential to retain CO2, as their favorable surface characteristics and the presence of iron oxides make them suitable for carbon capture technologies. Thin films of FAZs were deposited by in situ crystallization, and investigated for their morphology and optical sensitivity when exposed to pollutants in the gas phase, e.g., acetone. This study contributes to the development of novel technological solutions for the smart and valuable utilization of FA in the context of the circular economy and green energy production.

The effect of plasmonic structures having different shape and size on the light emission properties of color center containing nanodiamond structures was studied. The results show that these parameters are of great importance and can influence the luminescence intensity emitted by the color centers. The optimization of the plasmonic structure geometry for a specific color center can enhance efficiently the light-matter interaction, and the intensity of light emitted by the color center can be increased.

Diamond is a material with a number of outstanding mechanical, optical, electrical and chemical properties. In the last decade it has additionally attracted the attention of scientists due to the promising properties of the color centers in its crystal lattice which can find applications in quantum information technology or quantum sensing on a nanometer scale. In this contribution we present the most prominent color centers in diamond, namely the nitrogen-vacancy (NV) and the silicon-vacancy (SiV) centers, and the possibilities to create them in diamond. In order to increase the collection efficiency of the photons emitted by the color centers they should be incorporated in photonic structures. We demonstrate the fabrication of nanopillars with diameters down to 50 nm in nanocrystalline diamond (NCD) films and monocrystalline diamond. In order to reduce the photon scattering from the rough NCD surfaces we developed a planarization technique which significantly reduced the surface roughness.

Transplantation studies have pinpointed the circadian clock of the Madeira cockroach to the accessory medulla (AME) of the brain's optic lobes. The AME is innervated by approximately 240 adjacent neuropeptidergic neurons, including 12 pigment-dispersing factor (PDF)-expressing neurons anterior to the AME (aPDFMEs). Four of the aPDFMEs project contralaterally, controlling locomotor activity rhythms of the night-active cockroach. The present in vitro Ca2+ imaging analysis focuses on contralaterally projecting AME neurons and their responses to PDF, GABA, and acetylcholine (ACh). First, rhodamine-dextran backfills from the contralateral optic stalk identified contralaterally projecting AME neurons, which were then dispersed in primary cell cultures. After characterization of PDF, GABA, and ACh responses, PDF immunocytochemistry identified ipsilaterally and contralaterally projecting PDFMEs. All PDF-sensitive clock neurons, PDF-immunoreactive clock neurons, and the majority of ipsilaterally and contralaterally projecting cells were excited by ACh. GABA inhibited all PDF-expressing clock neurons, and about half of other ipsilaterally projecting and most contralaterally projecting clock neurons. For the first time, we identified PDF autoreceptors in PDF-secreting cockroach circadian pacemakers. The medium-sized aPDFMEs and all other contralaterally projecting PDF-sensitive clock cells were inhibited by PDF. The ipsilaterally remaining small PDF-sensitive clock cells were activated by PDF. Only the largest aPDFME did not express PDF autoreceptors. We hypothesize that opposing PDF signaling generates 2 different ensembles of clock cells with antiphasic activity, regulating and maintaining a constant phase relationship between rest and activity cycles of the night-active cockroach.

Osteoporosis causes bones to become weak and brittle. It is known that the alterations in bone metabolism associated to osteoporosis can impair bone healing around implants and affect their osseointegration. The main objective of this study was the development of new nanostructured implant materials based on ultrananocrystalline diamond (UNCD) coatings for enhancing osseointegration. The films were deposited on Ti substrates by microwave plasma CVD from 17% CH4/N2 gas mixtures and modified by O2 or NH3/N2 plasmas. The modifications rendered the H-terminated hydrophobic as-grown films hydrophilic. The interaction of endothelial (EA.hy926) and osteosarcoma (MG63) cells with differently modified UNCD surfaces was investigated by proteome analyses. It revealed the identification of over 19 000 proteins (extracellular and cytosolic). They correspond to 508 (Ti), 634 (UNCD), 651 (O-UNCD), and 668 (NH2-UNCD) protein groups. The interaction network analysis showed differences in the connectivity of inferred protein networks between the ECM niches, which suggests the presence of specific cell microenvironments on O- and NH2-terminated UNCD surfaces. Our results show that due to a favorable combination of surface chemical and topological properties the UNCD films, as-grown and especially after their plasma modifications, may serve as superior scaffolding for promoting the cell attachment and growth during osseointegration.

High-grade zeolite nanocomposites are synthesized utilizing solid by-products from combustion of coal for energy production in Thermal Power Plants applying alkaline aging, hydrothermal and fusion-hydrothermal activation procedures. The obtained coal ash zeolites were studied with respect to their chemical and phase composition, morphology, surface parameters and thermal properties. It was found that they are distinguished in nanocrystalline morphology and significant content of iron oxide nanoparticles (γ-Fe2O3, α-Fe2O3, γ-Fe3O4) and doping elements (Cu, Co, Mn, V, W, etc.) transferred from the raw coal ash, and therefore they are assumed as nanocomposites. Coal fly ash zeolite nanocomposites are characterized by a mixed micro-mesoporous texture, significant concentration of acidic Brønsted centers due to their high surface insaturation, high chemical and thermal stabilty. This unique combination of compositional and textural properties predetermines the application of these materials as catalysts for thermal oxidation processes, anticorrosion barrier coatings, carbon capture adsorbents, matrices for hosting functional groups, detergents etc. Examples for coal fly ash zeolite applications for substitution of critical raw materials in practice are provided.

Boron doped diamond (BDD) shows high chemical stability in contact with a liquid phase even under extreme pH conditions, high electrochemical activity, and allows very stable covalent functionalization on O- or N-terminated surfaces. It is therefore an excellent electrode material for many applications such as analytics, biosensors, and purification. Furthermore, the electrodes can be covalently functionalized with photo-sensitive dyes to generate photo currents. However, the energetic conditions and charge transfer mechanisms are not fully known and therefore have been investigated in this work. The focus was set on the energy band diagrams of nanocrystalline diamond (NCD) layers, especially on the flat-band potential VF and the band-bending ϕB in the space charge layer, for both O- and N-terminated surfaces, and the charge transfer mechanisms at the semiconductor/electrolyte phase-boundary, with or without electro-active organic dyes, such as manganese phthalocyanine. For this study NCD samples were grown by hot filament chemical vapor deposition (HFCVD) with a boron doping density NA ranging between 5.8 and 9.6 × 1020 cm−3. The pristine surface was then processed by oxygen or ammonia plasma to modify the termination to O and NH2, respectively. After that a series of Mott–Schottky plots was measured for both terminations at several frequencies spanning from 3 Hz to 10 kHz and in two different electrolytes, namely 0.1 M H2SO4 and 0.1 M KCl. The results showed nearly the same flat-band potential for both surface terminations, but a remarkable difference in the band-bending. The latter is most probably responsible for the better photoelectrical conversion observed in N-terminated NCD samples. The open-circuit potential (OCP) and chronoamperometric measurements performed after covalent functionalization of the samples with the color dyes revealed that only the N-terminated material delivered a measurable photocurrent. Although the global efficiency of the photoelectric conversion was low, these initial results show that by optimized selection of materials and modification technologies providing a proper match of the energy levels at all charge transfer steps, a higher energy output could be achieved.

Diamond and diamond-like carbon (DLC) films possess a set of excellent physical and chemical properties which together with a high biocompatibility make them attractive candidates for a number of medical and biotechnological applications. In the current work thin ultrananocrystalline diamond (UNCD) and DLC films were comparatively investigated with respect to cell attachment and proliferation after different surface modifications. The UNCD films were prepared by microwave plasma enhanced chemical vapor deposition, the DLC films by pulsed laser deposition (PLD). The films were comprehensively characterized with respect to their basic properties, e.g. crystallinity, morphology, chemical bonding nature, etc. Afterwards the UNCD and DLC films were modified applying O2 or NH3/N2 plasmas and UV/O3 treatments to alter their surface termination. The surface composition of as-grown and modified samples was studied by X-ray photoelectron spectroscopy (XPS). Furthermore the films were characterized by contact angle measurements with water, formamide, 1-decanol and diiodomethane; from the results obtained the surface energy with its dispersive and polar components was calculated. The adhesion and proliferation of MG63 osteosarcoma cells on the different UNCD and DLC samples were assessed by measurement of the cell attachment efficiency and MTT assays. The determined cell densities were compared and correlated with the surface properties of as-deposited and modified UNCD and DLC films.

Diamond nanopillars with diameters of 1 μm down to 50 nm have been fabricated from two types of diamond thin films, namely nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD) using electron beam lithography (EBL) and reactive ion etching (RIE) in an inductively coupled oxygen plasma (ICP). Aim of the study was to investigate the suitability of these pillars to incorporate nitrogen-vacancy (NV) color centers for applications in quantum information technology (QIT). The first part of the investigation is devoted to a characterization of the pillars, their shape, size, and properties. The second part of this investigation concerns the optical properties of NCD and UNCD nanopillars and the incorporation of NV centers within them. Among others, fluorescence mapping and photoluminescence measurements have been employed for this purpose. It turned out that NCD pillars are quite promising for the applications in QIT envisioned. At the present time, the opposite is the case for UNCD pillars. The reasons for these differences will be discussed on the basis of the differences of the two materials NCD and UNCD.

Thin boron-doped nanocrystalline diamond (NCD) films have been prepared by microwave plasma enhanced chemical vapour deposition (MPCVD) and used as platforms for grafting of photosensitizer (manganese phthalocyanine, Mn-Pc). The surface of the as-grown films is H-terminated; in order to modify it and study the influence of the termination on the attachment of Mn-Pc the NCD films were subjected to O2 plasma or NH3/N2 plasma treatments. Contact angle measurements and XPS results showed a successful exchange of the surface termination with OH- or NH2-groups. Manganese phthalocyanine molecules were grafted on the NCD surfaces with different terminations, after which each sample was subsequently characterized by XPS and Raman spectroscopy. Finally, the NCD/Mn-Pc samples were used for the preparation of electrodes which were tested in an electrochemical cell with a Pt counter electrode and an Ag/AgCl reference electrode; phosphate buffered saline was used as electrolyte. The characteristics of the electrodes were measured by cyclic voltammetry (CV) and open circuit potential (OCP) in dark and under illumination with a light-emitting diode (LED) operating at 770 nm (a wavelength close to the absorption maximum of Mn-Pc). The first results indicated that after plasma modifications NCD surfaces are suited for Mn-Pc grafting.

One-dimensional diamond nanostructures (diamond nanopillars) have been fabricated using nanocrystalline diamond films (NCD) as a starting material, and electron beam lithography (EBL) and reactive ion etching in an inductively coupled O 2 plasma (ICP-RIE) as processing techniques. In a first step, the etch rates have been determined as a function of four major plasma parameters, namely the ICP power, the rf power applied to the substrate holder, the pressure, and the oxygen flow rate. These parameters have been varied in wide ranges. In order to get insight into the mechanisms of the etching process, etching experiments have been performed with unpatterned NCD films by varying the process times using rather short intervals. Finally, EBL has been applied prior to the etching to obtain one-dimensional pillars with diameters from 200 nm to 1 μm. Scanning electron microscopy has been employed to characterize the pillars. First results showed the process developed to be successful, and first examples will be presented.

Two types of carbon-based films, namely diamond-like carbon (DLC) and ultrananocrystalline diamond (UNCD) films were comparatively investigated. The DLC films were prepared by pulsed laser deposition (PLD) without or with additional ion bombardment, the UNCD films by microwave plasma enhanced chemical vapour deposition. The films were characterized with respect to their topography and morphology (AFM, SEM) and bonding structure, e.g. fractions of sp3 and sp2 carbon atoms (XPS, FTIR and Raman spectroscopy). Finally, the wettability and the surface energies of both types of films were investigated with contact angle measurements as well as the antibacterial properties with two types of bacteria.

We have investigated the stability of the surface termination of ultrananocrystalline diamond/amorphous carbon (UNCD/a-C) composite films after their modification with UV/O 3 treatments or NH 3 -containing plasmas. The films were prepared by microwave plasma chemical vapor deposition from CH 4 /N 2 mixtures and possess the H-termination typical for all CVD grown diamond films. The treatment with UV/O 3 or NH 3 /N 2 plasma resulted in a change of the surface termination as revealed by contact angle measurements and X-ray photoelectron spectroscopy (XPS). Both processes rendered the as-grown hydrophobic UNCD surface hydrophilic; the influence of the treatment time as well as that of the carrier gas (N 2 or Ar) for the plasma process were investigated. The main task of this investigation was to determine the stability of the surface termination with storage time and storage conditions and upon exposure to standard organic solvents, like acetone, ethanol and i-propanol. It was found that for the UV/O 3 treated UNCD surfaces the storage in air, and after NH 3 /N 2 plasma modification package under reduced pressure preserved to a great extent the achieved hydrophilic properties in a period up to three months. The changes that occur predominantly during the first days after the modification step were due mostly to interchange of surface groups with the ambient. Similar processes were observed after exposure of the UNCD surfaces to standard organic solvents.

In this paper the low temperature deposition of nanocrystalline and ultrananocrystalline diamond (UNCD) films is compared and discussed. NCD films were prepared by hot filament chemical vapor deposition from a 1% CH4/H2 mixture, while microwave plasma chemical vapour deposition was used to deposit UNCD films from a mixture of 17% CH4/N2. The resulting films have been thoroughly characterized concerning their morphology and structure by scanning electron microscopy and concerning their crystalline properties by X-ray diffraction. The composition was analyzed by X-ray photoelectron spectroscopy (XPS), whereas XPS and Raman spectroscopy were applied to get information on the bonding structure of the films. The most important result of this study is that the composition, structure, morphology, and bonding environment of UNCD hardly change if the deposition temperature is lowered from 770 to 530 °C or even 450 °C. In contrast, there are drastic changes of the nature of NCD films if the temperature is reduced to 700 °C or even lower. Interestingly, the sp2/sp3 ratio of the NCD films remains low and constant in the temperature range investigated. Rather, the nature of the sp2 grain boundary material undergoes drastic changes if the temperature is lowered below 700 °C. In addition, the films become inhomogeneous on a micrometer (not nanometer) scale. Possible reasons for these observations will be discussed throughout the paper.

Ultrananocrystalline diamond (UNCD) films have been deposited by microwave plasma chemical vapor deposition from 17% CH4/N2 mixtures. In order to change the original hydrogen termination of the UNCD surfaces, the films have subsequently been subjected either to the so-called UV/O3 treatment which leads to OH-terminated surfaces, or to NH3/N2 plasmas which introduces NH2 groups but also a certain amount of OH groups. These three types of surfaces have been characterized by X-ray photoelectron spectroscopy, contact angle and ζ-potential measurements. The contact angle measurements have shown that as-grown UNCD surfaces are highly hydrophobic but became highly hydrophilic after both treatments. The ζ-potential measurements revealed that the isoelectric point of the H-terminated as-grown surface is distinctively higher than that of either UV/O3 or NH3/N2 plasma treated surfaces. Finally, the interactions of these surfaces with neurons of the cockroach Leucophaea maderae have been investigated. These studies have shown that especially the two treated surfaces allow for a fast, strong attachment of these cells without compromising their viability and without changing their normal physiological responses. These results will be discussed in terms of those obtained with the different surface characterization techniques.

Transformation from higher to ultra low friction coefficient was observed in ultrananocrystalline diamond film (UNCD) while changing the test atmospheric conditions. High friction coefficients were observed in dry argon and nitrogen atmosphere, however, low and ultra low friction coefficients were obtained in dry oxygen and in ambient atmospheric conditions, respectively. Wear rates follow the same trends as the friction coefficients. This fascinating behavior of friction and wear of UNCD film is explained by the chemical changes of sliding surfaces and extent of passivation of dangling covalent bonds.

Ultrananocrystalline diamond/amorphous carbon nanocomposite films (UNCD/a-C) have been deposited by microwave plasma chemical vapor deposition from a 17% CH4/N2 mixture. The films consist of diamond nanocrystallites of 3–5 nm embedded in an amorphous carbon matrix of 1–1.5 nm width. In a first series of experiments it is shown that as-grown UNCD/a-C films are hydrogen-terminated, conductive and very stable. Furthermore, by plasma- and photochemical treatments the H-termination can either be improved or replaced by terminating OH or F functionalities, whereas chemical room temperature processes to change the termination failed. A second set of investigations concerns the functionalization of differently terminated UNCD surfaces. Processes are discussed to bind DNA on H-terminated UNCD and to deposit an anti-fouling poly(ethylene glycol) layer on OH-terminated films. A third series of experiments shows that UNCD surfaces are not prone to unspecific interactions with highly-fouling proteins such as bovine serum albumin (BSA) but nevertheless some interaction will take place. However, the amount of adsorption and also the ratio of BSA and fibrinogen adsorption, which is of importance for the hemocompatibility of a surface, can be adjusted by the surface termination. Finally, it will be shown that continuous as-grown UNCD surfaces are bioinert and not cytotoxic for a variety of different cell lines.

The initial growth phase of ultrananocrystalline diamond/amorphous carbon nanocomposite films (UNCD/a-C) has been investigated by scanning electron microscopy, atomic force microscopy and especially Raman spectroscopy. As due to resonance effects Raman spectra of carbon materials strongly depend on the excitation wavelength, a multiwavelength analysis has been performed with λexc ranging from the UV region (325 nm) over the visible range (488 and 514 nm) to the IR region (785 nm). In addition, a set of measurements has been performed with a confocal Raman microscope, i.e. depth resolved, with a wavelength of 532 nm. The samples investigated were deposited with constant parameters, the deposition time being the only parameter varied, resulting in film thicknesses from 100 to 500 nm. It turned out that the diamond fraction and also the grain boundary material do not vary during that stage whereas there are slight but distinct changes of the nature of the amorphous matrix which reflect, among others, in a shift of the graphite-related G band to higher wavenumbers and in an increase of the ratio of D and G bands with increasing film thickness. These changes are discussed in terms of the above mentioned resonance effects; the major changes are a transition of hydrogen containing sp2 chains to hydrogen-free condensed sp2 rings when the material is no longer in the surface region of the films but becomes incorporated within the film bulk.

Thin arsenic-selenium-antimony films (AsSe)100−x Sb x (x=0,5,10,15 mol.%) have been deposited on glass substrates by vacuum thermal evaporation (VTE) and pulsed laser deposition (PLD) techniques from the corresponding bulk glassy materials. The refractive index and the film thickness have been determined from the optical transmission spectra by modified Swanepoel method. The optical band gap calculated using the Tauc’s approximation showed a narrowing as a function of the increased Sb content from 1.74 eV to 1.53 eV in the VTE films and from 1.64 eV to 1.42 eV in the PLD films. The refractive index of the Sb-doped films strongly increased with the Sb content and reached the largest value for the PLD films. The results verify that both techniques are suitable for deposition of thin glassy films with high optical quality.

Ultrananocrystalline diamond/amorphous carbon nanocomposite films (UNCD/a-C) have been deposited by microwave plasma chemical vapour deposition at 600 °C from 17% CH 4 /N 2 mixtures. The as-grown films turned out to be hydrogen terminated and very stable. Photochemical amination of H-terminated diamond is a well-established route to attach functional groups to such surfaces for applications in biosensors. Here we report on experiments to aminate UNCD surfaces directly by exposure to ammonia plasmas. Thereafter the surfaces were reacted with the heterobifunctional crosslinker molecule SSMCC bearing a N-hydroxysuccinimide (NHS) ester group which should react with the surface NH 2 groups. By means of X-ray photoelectron spectroscopy (XPS), contact angle measurements and fluorescence microscopy it is shown that both steps, plasma amination and SSMCC attachment lead to the desired aims. On the other hand, experiments to attach a thiol-bearing fluorescein molecule directly to H-terminated UNCD films turned out to be partially successful although according to literature such a reaction should be very unlikely.

In the present study, we have compared the effects of ultrananocrystalline diamond/amorphous carbon composite films (UNCD/a-C) and nanocrystalline diamond (NCD) containing hydrogels to support the osteogenesis of endothelial progenitor cells (EPCs). The course of EPCs osteogenic differentiation was followed 21 days and assayed by measuring cell-associated alkaline phosphatase activity, calcium deposition, and expression of fibronectin. We found that EPCs were capable to adhere to both surfaces in flattened and elongated morphology. The attachment and spreading on the UNCD/a-C films were faster as compared to the hydrogels containing NCDs (by day 7), and this was connected with the release and adsorption of fibronectin to the surfaces. During the process of EPCs differentiation, the release of fibronectin was favored by hydrogels + NCD (day 21). The formation of calcium nodules, characteristic of osteoblastic mineralization, was detected by Alizarin Red S staining. Differentiation-induced calcium nodules were detected in EPCs growing on both surfaces. The EPCs cultured on hydrogels containing NCD deposited more extracellular calcium in comparison with those on UNCD/a-C films on day 21. These results were consistent with the data about the alkaline phosphatase activity on the same day and verified that an active EPC transformation to osteoblast phenotype occurred on both substrates. Our results could have direct implications in the use of biomaterials in tissue engineering strategies, and this work might be useful for the improvement of the methodologies for substrate preparation (including scaffolds). Thus both surfaces studied could be used for modification of bone implants (bone-anchoring parts of joint prostheses or bone replacements) in order to improve their integration with the surrounding bone tissue, for which improved cell–substrate adhesion is also needed.