Hiroshi Koshikawa

FTIR reflection absorption spectroscopy for organic thin film on ITO substrate

Abstract Dielectric constant of indium–tin oxide (ITO) substrate was obtained by the basis of free electron model to evaluate the reflection infrared (IR) spectrum of an organic thin film on the ITO substrate in the wavenumber region from 3500 to 600 cm−1. In a wavenumber region of less than 2000 cm−1, the given spectrum was approximate to the spectrum on a metal substrate having high reflectivity. In this region, the thickness of the PVCz thin film under physical vapor deposition process was proportional to the peak intensity of reflection spectrum.

Real-time in situ observation of photo-induced vapordeposition polymerization of N-vinylcarbazole with Fourier transform IR reflection absorption spectroscopy

Abstract By using a low pressure mercury lamp as an excitation source, vapor deposition polymerization (VDP)of N-vinylcarbazole was carried out. Deposition and annealing processes were observed with real-time in situ Fourier transform IR reflection absorption spectroscopy. On average, the film deposited at the substrate temperature of 255–275 Kconsisted of 65% of an isotropic component and 35% of an oriented component. A polymer yield of 95% film was obtained at a substrate temperature of 275 K. The same yield was achieved at an annealing temperature of around 350 K when the VDP film deposited at 255 K was annealed in vacuum.

Radiation-induced reactions via the lowest excited states in cinnamic acid crystals

Radiation-induced reactions of cinnamic acid derivatives have been examined and compared with photoreactions in the crystalline state; all the reaction products were exactly the same as those of the photoreactions, indicating that the reactions proceed only via the lowest excited state to give [2 + 2] cycloadducts, E/Z isomerization products, or starting molecules.

Conductometric Analysis for the Formation of Poly(Vinylidene Fluoride)-Based Ion Track Membranes

Poly(vinylidene fluoride) (PVDF) films were irradiated with 450 MeV Xe and 2.2 GeV Au ion beams, and then the resulting latent tracks were etched in a 9 mol dm aqueous KOH solution at 80oC that had been poured into a conductometric cell. At the same time, the evolution of cylindrical nanopores was monitored by measuring the conductance through the membrane. This in-situ measurement enabled us to examine how the etching kinetics were affected by the various experimental conditions including the parameters (mass and velocity) of the bombarded ions and cell voltages applied between the electrodes. The track etch rate, VT, radial etch rate, VR, and pore radius reaching the final plateau significantly depended on the deposited energy within each track, which is represented by the linear energy transfer (LET). Interestingly, applying a higher voltage to the cell promoted track etching up to the breakthrough probably because the electrophoretic migration of dissolved products occurred out of each pore.

Ion Beam Modification of Pt Electrocatalyst Nanoparticles for Polymer Electrolyte Membrane Fuel Cells

Platinum (Pt) nanoparticles were prepared on a glassy carbon plate by a sputtering method and then irradiated with proton (H + ) beams at energies of 0.38 and 10 MeV at room temperature. Cyclic voltammetry in an aqueous 0.5 mol/dm 3 H 2 SO 4 solution suggested that the lower-energy beam irradiation enhanced the active surface area of the Pt nanoparticles, calculated from the coulombic charge for hydrogen desorption. Thus, the nanoparticles would be modified by H + beam-induced electronic excitation so that they have higher surface activity. The mechanism of this irradiation effect seems to be rather complicated and is still unclear at present, but we may discuss it in relation to a change in the interfacial crystal structure during the irradiation.