Oxygen Cluster Ion Beams Research Articles

Detection of ZrO₂ Nanoparticles in Lung Tissue Sections by Time-of-Flight Secondary Ion Mass Spectrometry and Ion Beam Microscopy.

The increasing use of nanoparticles (NP) in commercial products requires elaborated techniques to detect NP in the tissue of exposed organisms. However, due to the low amount of material, the detection and exact localization of NP within tissue sections is demanding. In this respect, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Ion Beam Microscopy (IBM) are promising techniques, because they both offer sub-micron lateral resolutions along with high sensitivities. Here, we compare the performance of the non-material-consumptive IBM and material-consumptive ToF-SIMS for the detection of ZrO2 NP (primary size 9–10 nm) in rat lung tissue. Unfixed or methanol-fixed air-dried cryo-sections were subjected to IBM using proton beam scanning or to three-dimensional ToF-SIMS (3D ToF-SIMS) using either oxygen or argon gas cluster ion beams for complete sample sputtering. Some sample sites were analyzed first by IBM and subsequently by 3D ToF-SIMS, to compare results from exactly the same site. Both techniques revealed that ZrO2 NP particles occurred mostly agglomerated in phagocytic cells with only small quantities being associated to the lung epithelium, with Zr, S, and P colocalized within the same biological structures. However, while IBM provided quantitative information on element distribution, 3D ToF-SIMS delivered a higher lateral resolution and a lower limit of detection under these conditions. We, therefore, conclude that 3D ToF-SIMS, although not yet a quantitative technique, is a highly valuable tool for the detection of NP in biological tissue.

Low-temperature formation of silicon dioxide films by oxygen cluster ion beam assisted deposition

Silicon dioxide films were formed by the cluster ion beam assisted deposition method. An oxygen cluster ion beam was irradiated while a silicon monoxide vapor was deposited on a substrate at room temperature. The deposited films were oxidized to form silicon dioxide films when the beam current density of the oxygen cluster ion beam was larger than 500 nA/cm 2 and the acceleration voltage of the oxygen cluster ion beam was higher than 3 kV.

Chemical Modification of Silicone Rubber by Oxygen Cluster and Monomer Ion Beams

Chemical Modification of Silicone Rubber by Oxygen Cluster and Monomer Ion Beams

Induction of bioactivity on silicone elastomer by simultaneous irradiation of oxygen cluster and monomer ion beams

Silicone elastomer substrates were irradiated with acceleration voltages ranging from 3 to 9kV and doses ranging from 1×1014 to 2.5×1015ionscm−2 by the simultaneous use of oxygen cluster and monomer (O2 CM) ion beams, and then soaking in CaCl2 solution. The apatite-forming ability of the substrates was examined using a metastable calcium phosphate solution that had 1.5 times the ion concentrations of normal simulated body fluid (1.5SBF). Silicon oxide clusters (SiOx) were formed at the silicone elastomer surfaces and the hydrophilicity of the substrates was remarkably improved by the irradiation. The irradiated silicone elastomer substrates formed apatite in 1.5SBF, whereas unirradiated ones did not. These results suggest that irradiation using O2 CM ion beams is effective for inducing an apatite-forming ability on silicone elastomer substrates.

Photocatalytic properties of Cr-doped TiO 2 films prepared by oxygen cluster ion beam assisted deposition

We prepared Cr-doped titanium dioxide (TiO 2) films by oxygen (O 2) cluster ion beam assisted deposition method, and investigated photocatalytic properties of the films as well as crystallographic property, optical property and surface morphology. The films prepared at a substrate temperature below 200 °C were found to be amorphous from the X-ray diffraction measurement. For the substrate temperatures such as 300 °C and 400 °C, the films exhibited rutile and/or anatase structures. The film surface measured by the atomic force microscope (AFM) was smooth at an atomic level. Furthermore, the optical band gap decreased with increase of Cr-composition, and it was approximately 3.3 eV for the non-doped films, 3.2 eV for the 1% Cr-doped films and 3.1 eV for the 10% Cr-doped films, respectively. With regard to the photocatalytic properties of the Cr-doped TiO 2 films, we measured the change of contact angle as well as the photocatalytic degradation of methylene blue by the UV light irradiation. Compared with the non-doped films, the 1% Cr-doped films prepared at a substrate temperature of 400 °C showed high degradation efficiency. In addition, the contact angle of the 1% Cr-doped films with an initial value of 60° decreased to 10° by the UV light irradiation for 20 min, and the films exhibited the predominant properties of photocatalytic hydrophilicity even for the UV light irradiation with longer wavelengths.

Surface Structure and Apatite-Forming Ability of Silicone Rubber Substrates Irradiated by Cluster Ion Beams

Silicone rubber substrates were irradiated at an acceleration voltage of 7 kV and a dose of 1×1015 ions/cm2 by the simultaneous use of oxygen cluster and monomer ion beams, and then soaked in CaCl2 solution. Apatite-forming ability of the substrates was examined using a metastable calcium phosphate solution that had 1.5 times the ion concentrations of a normal simulated body fluid (1.5SBF). After the irradiation, the silicon oxide clusters (SiOx) were formed at the silicone rubber surface. The hydrophilicity of the substrates was remarkably improved by the irradiation. The irradiated silicone rubber substrates formed apatite in 1.5SBF, whereas unirradiated ones did not form it. These results suggest that the functional groups such as Si–OH and/or COOH groups induced apatite nucleation in 1.5SBF.

Surface structure and apatite‐forming ability of polyethylene substrates irradiated by oxygen cluster ion beams

Polyethylene (PE) substrates were irradiated at a dose of 1 x 10(15) ions/cm(2) by the simultaneous use of oxygen (O(2)) cluster and monomer ion beams. The acceleration voltage for the ion beams was varied from 3 to 9 kV. Unirradiated and irradiated PE substrates were soaked for 7 days in a metastable calcium phosphate solution (1.5SBF) that had 1.5 times the ion concentrations of a normal simulated body fluid. The irradiated PE substrates formed apatite on their surfaces, irrespective of the acceleration voltage, whereas unirradiated substrates did not form apatite. This is attributed to the formation of functional groups that are effective for apatite nucleation, such as --COOH groups, on the substrate surface by the simultaneous use of O(2) cluster and monomer ion beams. The apatite-forming ability of the irradiated PE substrates was improved greatly by a subsequent CaCl(2) solution treatment. This suggests that Ca(2+) ions introduced on the substrate surface by the CaCl(2) solution treatment accelerated the apatite nucleation. It is concluded that apatite-forming ability can be induced on the surface of PE by the simultaneous use of O(2) cluster and monomer ion beams.

Apatite-Forming Ability of Polymer Substrates Irradiated by Oxygen Cluster Ion Beams

Polyethylene (PE) substrates were irradiated at a dose of 1×1015 ions·cm−2 by the simultaneous use of oxygen (O2) cluster and monomer ion beams. The acceleration voltage for the ion beams was 7 kV. Unirradiated and irradiated PE substrates were soaked in simulated body fluid with ion concentrations 1.5 times of those of human blood plasma (1.5SBF) for 7 days. The irradiated PE substrate formed apatite on its surface, whereas unirradiated one did not form it. This is attributed to the formation of functional groups effective for apatite nucleation, such as COOH groups, on the substrate surface by the simultaneous use of O2 cluster and monomer ion beams. In addition, the apatite-forming ability of the irradiated substrate was improved by the subsequent CaCl2 treatment. This suggests that Ca2+ ions present on the substrate surface accelerated the apatite deposition. We can conclude that apatite-forming ability can be induced on surface of polyethylene by the simultaneous use of O2 cluster and monomer ion beams.

In Vitro Apatite Formation on Polymer Substrates Irradiated by the Simultaneous Use of Oxygen Cluster and Monomer Ion Beams

AbstractPolyethylene (PE) and silicone rubber substrates were irradiated at an acceleration voltage of 7kV and a dose of 1×1015 ions/cm2 by the simultaneous use of oxygen cluster and monomer ion beams, and then soaked in CaCl2 solution. Apatite-forming ability of the substrates was examined using a metastable calcium phosphate solution that had 1.5 times the ion concentrations of a normal simulated body fluid (1.5SBF). After the irradiation, the hydrophilic functional groups such as COOH and silicon oxide cluster (SiOx) were formed at the PE and silicone rubber surfaces, respectively. The hydrophilicity of the substrates was remarkably improved by the irradiation. The irradiated PE and silicone rubber substrates formed apatite in 1.5SBF, whereas unirradiated ones did not form it. These results suggest that the functional groups such as COOH groups and Si-OH groups induced apatite nucleation in 1.5SBF.

Apatite Deposition on Polymer Substrates Irradiated by Oxygen Cluster Ion Beams

Polyethylene (PE) and polyethylene terephthalate (PET) substrates were irradiated by the simultaneous use of oxygen (O 2 ) cluster and monomer ion beams to improve their hydrophilic property. The hydrophilic groups such as COOH and C-OH groups were formed at the PE and PET surfaces by the irradiation. The contact angles of PE and PET substrates were decreased remarkably by the irradiation. Bioactive calcium silicate (CS) gel layer was successfully formed on the irradiated PE and PET substrates, and the irradiated and CS-coated PE and PET substrates formed uniform bonelike apatite layer on their surfaces in SBF within 4 d.

Photocatalytic properties of TiO 2 films prepared by O 2 cluster ion beam assisted deposition method

Titanium dioxide (TiO 2) films were prepared on Si(1 0 0) substrate by oxygen (O 2) cluster ion beam assisted deposition method. The TiO 2 films prepared at a substrate temperature of 200 °C or less were amorphous, whereas those at a substrate temperature of 300 °C contained both rutile and anatase. The refractive indexes of the TiO 2 films increased with increasing substrate temperature. The surface state of the TiO 2 film was smooth at an atomic level. The TiO 2 films prepared at a substrate temperature of 300 °C showed high photocatalytic decomposition of methylene blue by ultraviolet (UV) irradiation, similar to those of TiO 2(1 0 0) bulk state in a rutile structure. The contact angle of the TiO 2 film with an initial value of 75° decreased to 10° by UV irradiation for 30 min, although that for TiO 2(1 0 0) bulk state in rutile structure remained at the initial value even after the UV irradiation. It is considered that anatase in the TiO 2 films was contributed to both photocatalytic decomposition and photocatalytic hydrophilicity of the films.

Bonelike apatite formation on polyethylene surface irradiated by oxygen cluster ion beam

Bonelike apatite formation on polyethylene surface irradiated by oxygen cluster ion beam

Optical thin film formation by oxygen cluster ion beam assisted depositions

O2 gas cluster ion beam (O2-GCIB) assisted depositions were employed to deposit high quality dielectric films (Ta2O5, Nb2O5 and SiO2). The optimum irradiation energy and ion current density for Ta2O5 films were 5 to 9keV and 0.5μA/cm2, respectively. The Ta2O5/SiO2 films deposited with O2-GCIB irradiation showed very uniform and dense structures without columnar or porous structures. Due to the significant surface roughness improvement effect of GCIB, the surface roughness decreased even though the films were deposited on a rough surface. The Nb2O5/SiO2 interference filter deposited with O2-GCIB assisted deposition was very stable and there was no shift of wavelength before and after environmental tests.

Improvement of surface roughness by ultra-thin film deposition with oxygen cluster ion beam assist deposition

ABSTRACTTa2O5 films were deposited on a rough surface (average roughness 1.3nm, peak-to-valley 14nm) and surface roughness evolutions and improvements by O2 gas cluster ion beam (O2-GCIB) assisted deposition was studied. The average roughness dramatically decreased from 1.3nm to 0.5nm after deposition of Ta2O5 films 20nm in thickness with 7 keV of O2 cluster ion beams. As there was no etching or sputtering of Ta2O5 film by 7keV O2-GCIB irradiations, O2-GCIB assist deposition realized significant improvement of surface roughness by additional deposition of Ta2O5 film whose thickness was close to the peak-to-valley of original surface. It is expected that morphological evolution of the film by GCIB assist deposition becomes completely different from conventional ion assist deposition due to energetic cluster ion impacts.

O 2 cluster ion-assisted deposition for tin-doped indium oxide films

In order to realize high throughput for industrial application, a new gas cluster ion-assisted deposition system has been developed. Tin-doped indium-oxide (ITO) films were formed by using the O 2 gas cluster ion beam-assisted deposition technique. Large oxygen cluster ions which can transport thousands of atoms in an ion with very low energy per constituent atom were used in this deposition process. The energetic oxygen clusters collapse at the surface and react with the metal atoms. About 10% of atoms are incorporated, when the kinetic energy of the cluster ion is above 5 keV. Interactions between cluster ions and substrate atoms occur in the near-surface region and cluster ions can deposit their energy with a high density in a very localized surface region. The oxidation reaction on the surface can be enhanced by energetic cluster ion bombardment which offers a new technique for ion-assisted thin film formation. Very smooth, highly transparent (>80%) and low resistivity films were obtained by using a 7 keV oxygen cluster ion beam.

High-intensity oxygen cluster ion beam generation and its application to cluster ion-assisted deposition

Oxide film formation using high-intensity oxygen cluster ion beams has been developed. This deposition process uses large cluster ions, which can transport thousands of atoms per ion with very low energy per constituent atom. As a result, the interactions between the cluster and substrate atoms occur in the near-surface region, and cluster ions can deposit their energy with a high density in a very localized surface region. Enhancement of the oxidation reactions is clearly demonstrated. High-quality tin-doped indium-oxide (ITO) films, which are widely used in electrical and optical devices, are formed. Very smooth, highly transparent (>80%) and low-resistivity (< 4 × 10−4 Ω cm, which are the lowest values for films grown at room temperature) films, were obtained by the use of a 7 keV oxygen cluster ion beam. The energetic oxygen clusters collapsed at the surface and reacted with the metal atoms, and about 10% of them were incorporated when the kinetic energy of the cluster ion was above 5 keV. Oxidation reaction can be enhanced by energetic cluster ion bombardment, which offers a new technique for ion-assisted thin-film formation.

High Quality Oxide Film Formation by 02 Cluster Ion Assisted Deposition Technique

ABSTRACTA new oxide film formation technique using gas-cluster ion beams has been developed. 02 cluster ions were used to irradiate during the evaporation of metal atoms, and PbOx and In203 films were grown. At the acceleration voltages above 5 kV, polycrystalline PbOx films preferentially oriented to (111) were obtained. A significant smoothing effect was observed with an acceleration voltage as low as 1 kV. An average surface roughness of 0.9 nm was obtained at 7 kV. Oxygen cluster ion beams are also utilized to grow In203 films, which are widely used as conductive-transparent films in flat panel display. In203 was deposited on glass or silicon substrates with simultaneous irradiation with an oxygen cluster ion beam. Highly transparent (80%) and low resistivity (&lt;4×10−4 Ωcm) films were obtained with 7keV oxygen cluster ion beams. Kinetic energy of above 3keV is necessary to obtain low resistivity films. These results clearly indicate that the kinetic energy of the cluster is effectively used to enhance oxidation on the surface without radiation damage, in spite of the high acceleration voltages.