e-Journal of Surface Science and Nanotechnology Vol. 13(2015)

Zn doped strontium germanate has been prepared by the hydrothermal method using strontium acetate, germanium dioxide and zinc acetate as the raw materials. The Zn doped strontium germanate were analyzed by X-ray diffraction, scanning electron microscopy and solid UV-vis diffuse reflectance spectrum. The structures of Zn doped strontium germanate were confirmed to be hexagonal SrGeO₃ and rhombohedral ZnGeO₃ phases. The band gap of Zn doped strontium germante decreases from 3.67 eV to 2.88 eV with the change of the Zn doping mass percentage. The photocatalytic activity of the Zn doped strontium germanate has been evaluated for the photocatalytic degradation of gentian violet under UV light irradiation. The results reveal that the Zn doped strontium germanate has the enhanced photocatalytic activity. [DOI: 10.1380/ejssnt.2015.8]

The increasing importance of the volume expansion effect on crystalline materials induced by ion-beam irradiation has drawn much attention because of its applications. For example, the expansion effect is used as a good probe to investigate any crystalline-amorphous (c-a) phase change and/or damage. Because the expansion rate and its depth profile can be controlled by means of the irradiation parameters, such as fluence and energy, the deformation of structures on the micro-/nano-meter scale is expected. The fluence needed to achieve deformation is relatively low, and it is expected that irradiation-induced damage is reduced compared with that induced by conventional ion-beam fabrication. Therefore, this expansion effect is a potential method to improve the ion-beam technology employed to fabricate complicated 3-dimensional structures requested in actively developing industrial fields, such as MEMS/NEMS. [DOI: 10.1380/ejssnt.2014.35]

We study the electronic transport properties of armchair graphene nanoribbons with a width of up to 12 nm bridged between two Au electrodes using first-principles calculations. The transport properties sensitively depend on the ribbon width, even though the width reaches 12 nm. The variation of transport properties is ascribed to the detailed electronic structures of graphene ribbons, which sensitively depend on their width. The band structure and the symmetry of π state of the graphene play important roles in determining the transport properties. [DOI: 10.1380/ejssnt.2015.54]

We studied the electronic, structural, and electrochemical modulation of electrostatic self-assembled thin films in which a nanoscale pair of single layer 1T-MoS₂ nanosheets and charge-compensating polymers as a counterpart in the self-assembly process stacked up on the substrate after heating. Heating the self-assembled monolayer and multilayers of the 1T-MoS₂ nanosheets at 300°C under vacuum triggered a yellow coloration and structural transformation, referred to as the 1T→2H transition, without a significant morphological change. In the topotactic conversion, an energy shift of the Mo 3d and S 2p core levels to a higher binding energy corresponds to the edge shift of the valence band, indicating the unique nature of this system as a MoS₂ molecule. The single layer state, which is often modulated by stacking the metallic-like 1T-MoS₂ nanosheets and the semiconductor 2H-MoS₂ nanosheets, was retained in the multilayers due to the robust interlayer galleries filled by the polymers. Cyclic voltammograms of a Li-ion battery using the 1T- or 2H-MoS₂ multilayer film electrodes provided useful information on the electrochemical reaction of the MoS₂ slabs, especially at the early stage of electrochemical Li insertion. These self-assembled ultra-thin films, offering well-defined MoS₂ nanosheet structures in terms of stacking order and crystal structure, will promote future applications of the single-layer 1T- and 2H-MoS₂ nanosheets. [DOI: 10.1380/ejssnt.2015.1]

This paper proposes a method for fabricating gadolinium diethylenetriamine pentaacetic acid-immobilized silica particles (SiO₂/Gd-DTPA). Preparation of a colloid solution of spherical silica particles with an average size of 101.7±11.7 nm was performed by a sol-gel method at 35°C using 0.2 M tetraethylorthosilicate, 25 M H₂O and 0.01 M NaOH in ethanol. Amino groups were introduced on the silica particles with 6 × 10⁻³ M (3- aminopropyl)triethoxysilane (APES) at 35°C (SiO₂-NH₂), which resulted in their average particle of 80.5±9.7 nm. Gd-DTPA was immobilized on the SiO_2-NH₂ particle surface with 5 × 10⁻⁴ M Gd-DTPA in 50/50 (v/v) water/dimethylformamide solution at 35°C , which provided their average particle of 101.6±12.3 nm. The APES-introduction and the Gd-DTPA-immobilization did not change the spherical structure, and shifted an iso-electric point of particles to higher pH for the APES-introduction and then to lower pH for the Gd-DTPA-immobilization, which indicated that APES and Gd-DTPA were successfully attached on the particle surface with no chemical damage. A relaxivity value for T₁-weighted imaging of the SiO₂/Gd-DTPA particle colloid solution was 2.7 mM⁻¹ s⁻¹, that was 64% of that for Magnevist. [DOI: 10.1380/ejssnt.2015.42]

Inorganic-organic composite materials are commercially utilized over a wide variety of industrial fields. The information on the distribution of inorganic and organic components on a nanometer scale is important for understanding the chemistry of the composite materials. In this study, the distribution of polycarbonate (PC) oligomer within a glass fiber reinforced PC was investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and principal component analysis (PCA). As a result, PCA indicated a component differentiating PC oligomer from PC polymer and revealed the homogeneous distribution of PC oligomer within the glass fiber reinforced PC. Therefore, a combination of ToF-SIMS and PCA is useful for identifying the detailed distribution of PC oligomer and evaluating the property of glass fiber reinforced PC. [DOI: 10.1380/ejssnt.2015.47]

Electronic structures of donor-acceptor hetero-interfaces are crucial for performance of organic solar cell devices. In the present study, a well-defined organic molecular interface of pentacene single crystal and C₆₀ overlayer is elucidated by x-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) and photoelectron yield spectroscopy (PYS). An energy level diagram at this hetero-molecular contact in the “head-on” orientation is derived, which reveals the vacuum level alignment and flat-band conditions. [DOI: 10.1380/ejssnt.2015.59]

Three-dimensional microanalysis of the microstructure of organic materials is important in the development and progress of novel materials on the micro-to-nanometer scales. We have developed the three-dimensional microanalysis method using focused ion beams (FIBs) for section processing (shave-off scanning) and mapping for time-of-flight secondary ion mass spectrometry (ToF-SIMS). Shave-offscanning can effectively create an arbitrary section on a sample set against composite materials with a wide variety of shapes; three-dimensional sample images are then obtained by alternately operating two FIBs. From the simulation results, we could set the optimum condition of beam irradiation. In this study, we confirmed the enhancement of secondary ion intensity by Au deposition under ToF-SIMS mapping with the optimized condition, and examine the usefulness of the simulation. The enhanced maps of characteristic polystyrene (PS) fragment ions were obtained. In addition, we observed the distribution of Au deposition by mapping results. These maps showed same tendency. The intensity of PS fragment ions was enhanced according to existence of deposited Au particles. These results indicated that a precise analysis of 3D MetA-SIMS can be realized. [DOI: 10.1380/ejssnt.2015.65]

We examined the photometric characteristics of ultraviolet light (UV) measurements of aqueous solution and polyvinyl alcohol (PVA) film containing bromothymol blue (BTB) and diphenyliodonium salts (chloride, nitrate and trifluoromethane sulfonate). The solution and film were initially green (neutral), but were changed to yellow (acidic) by irradiation with 254 nm UV from a mercury lamp. A solution and film containing only BTB did not show the color change, which we concluded was solely induced by the acid generation from the diphenyliodonium salts. Photochemical kinetics of the UV-induced color change are discussed on the basis of experimental results; the color change proceeded obviously according to pseudo-first-order kinetics. This BTB/diphenyliodonium salt system could be used as a low-cost, mobile UV dosimeter. [DOI: 10.1380/ejssnt.2015.15]

We used a self-organized polymer microhoneycomb structure as a template to form polyaniline structures that contain hexagonal voids. The polyaniline was synthesized in situ and adsorbed spontaneously on a polymer honeycomb structure that was immersed in the solution. Successive adsorption cycles led to thicker polyaniline coating. The characteristic honeycomb structure could be preserved during the process. Electrical measurements showed that the film resistance is the sum of contact and sheet resistance. [DOI: 10.1380/ejssnt.2015.19]

Terbium oxide nanoparticles, TbO_x nanoparticles, were synthesized by the thermal reaction of Tb(III) complexes as a single-source precursor with acetylacetone (acac) or hexafluoroacetylacetone (hfa). Thermal decomposition processes of Tb(III) complexes for preparation of TbO_x nanoparticles were characterized by the thermogravimetric analysis (TGA). The prepared TbO_x nanoparticles were identified using XRD and TEM measurements. [DOI: 10.1380/ejssnt.2015.23]

Series of nonanuclear Tb(III) clusters with ligands of different length of alkyl chain groups and their photophysical properties are demonstrated. The nonanuclear Tb(III) clusters (Tb₉ clusters) are composed of nine oxygen-bridged Tb(III) ions and sixteen alkyl salicylate ligands, where alkyl chain are ethyl (Tb₉-Et), propyl (Tb₉-Pr), butyl (Tb₉-Bu), and hexyl (Tb₉-Hex) groups. The luminescence properties of the Tb₉ clusters are characterized by absorption spectra, emission quantum yields, and emission lifetimes. The radiative (k_r) and nonradiative (k_nr) rate constants were calculated from their photophysical properties. Tb₉-Hex have shown the highest k_r (859 s^-1) and lowest k_nr (137 s^-1), owing to the tight packing due to CH-π interaction by long alkyl chains. [DOI: 10.1380/ejssnt.2015.27]

The chiroptical properties of nonanuclear Tb(III) clusters are reported. The nonanuclear Tb(III) clusters are composed of nine Tb(III) ions, ten μ-OH parts, and sixteen chiral organic ligands, (±)-bornyl salicylate. Their chiroptical properties were estimated by circular dichroism (CD) and circularly polarized luminescence (CPL). Their electronic structures were calculated using TD-DFT (B3LYP/6-31G(d)) method. [DOI: 10.1380/ejssnt.2015.31]

Europium ions were doped in silica glass matrix with a sol-gel method as well as Al co-dopant. The samples densified at 1050°C showed bright blue emission under UV illuminations. Lifetime of the luminescence was about 1 μs and did not depend on Al concentration, indicating that europium existed as divalent form at proximate positions to aluminum ions. [DOI: 10.1380/ejssnt.2015.51]

Investigation for the operation mechanism in writing and reading processes are necessary in order to realize practical 3D devices with azo-carbazole dyes which are promising candidates for real-time 3D displays. We made dynamical studies of four-wave mixing and two-beam coupling for dyes 3-[(4-nitrophenyl)azo]-9H-calbazole-9-ethanol (NACzEtOH) and Disperse Red (DR1) doped in a polymer and investigated their dependence on dye concentration. Results indicated the important roles of birefringence on the holographic response and stable but erasable characteristics of the gratings in the azo-carbazole. [DOI: 10.1380/ejssnt.2015.69]