In situ measurements of emission transition dipole moment of individual ordered microdomain of diprotonated tetraphenylporphine aggregate formed at dodecane/aqueous H<Subscript>2</Subscript>SO<Subscript>4</Subscript> interface

Rhombic-ordered microdomains of diprotonated 5,10,15,20-tetraphenylporphine aggregate, whose sizes were 10–200 μm, were formed at dodecane/aqueous H₂SO₄ interfaces. The light excitation of their two absorption bands (410 and 473 nm for H- and J-bands, respectively) led to one fluorescence band at longer wavelength (723 nm). The direction of the emission transition dipole moment (μ _e) of individual rhombic microdomains, determined with an in situ optical microscope and a linear polarizer, was almost parallel to the major axis, which was also almost parallel to the direction of the absorption transition dipole moment of their J-bands. Their absorption and emission transition scheme was proposed.     

Study on solid structure of pentacene thin films using Raman imaging

We present a 532‐nm excited Raman imaging study of pentacene thin films (thickness, 2, 5, 10, 20, 50, 100, and 150 nm) prepared on an SiO₂ surface. The structure of the pentacene films has been investigated by images and histograms of the ratio (R) of intensity of the 1596‐cm⁻¹ band (b_3g) to that of the 1533‐cm⁻¹ band (a_g), which can be used as a marker of solid‐state phases: 1.54‐nm and 1.44‐nm phases. The Raman images showed that island‐like 1.44‐nm phase domains are grown on the 1.54‐nm phase layer from 50 nm, and all the surface of the 1.54‐nm phase layer is covered with the 1.44‐nm phase layer from 100 nm. The structural disorders have been discussed on the basis of the full width at half maximum of a band in the histogram of the R values for each film. Copyright © 2012 John Wiley & Sons, Ltd.     

Low loss smart hollow waveguides with new polymer coating material

A new kind of cyclic olefin polymer COP-E48R has been selected as the dielectric material for a silver hollow glass tube. Owing to its lower extinction coefficient at the wavelength of 10.6 μm, transmission losses for the CO₂ laser light has been reduced significantly in the COP-E48R-coated silver (COP-E48R/Ag) hollow glass waveguide. By properly selecting the film thickness of COP, Er:YAG and CO₂ laser light are shown to be transmitted with low loss simultaneously or independently. Delivery properties of red and green pilot beams were also evaluated.     

Voltage-induced infrared spectra from polymer field-effect transistors

Charge-induced infrared absorption spectra from the metal-insulator-semiconductor diodes fabricated with aluminum oxide, poly(p-xylylene), and SiO₂ as gate dielectric and regioregular poly(3-octylthiophene) as organic semiconductor have been measured in situ with reflection or transmission configurations by the FT-IR difference-spectrum method. The observed bands have been attributed to the carriers injected into the polymer layers under the application of minus gate bias. The wavenumber of the band around 1300 cm⁻¹ depends on the gate voltage, indicating that the structure of the carriers depends on the carrier concentration. There exist upper limits in the concentrations of the injected carriers. In situ infrared absorption measurements provide the information about the injected carriers, which affect the properties and the functions of polymer field-effect devices.