This paper deals with off-diagonal operator matrices and their applications in elasticity theory. Two kinds of completeness of the system of eigenvectors are proven, in terms of those of the compositions of two block operators in the off-diagonal operator matrices. Using these results, the double eigenfunction expansion method for solving upper triangular matrix differential systems is proposed. Moreover, we apply the method to the two-dimensional elasticity problem and the problem of bending of rectangular thin plates on elastic foundation.

Optical absorption measurements at high pressure were extended up to 5.5 eV in the ultraviolet region by constructing an ultraviolet-visible-near infrared absorption spectrometer adapted for diamond anvil cells and by using impurity free synthetic diamonds. Using the improved spectrometer, absorption spectra of solid hydrogen sulfide (H2S) were measured under various pressures from 0.3 to 29 GPa at room temperature. The band gap estimated from the absorption edge was 4.8 eV at 0.3 GPa and decreased to 2.7 eV at 29 GPa almost linearly except for a small jump at about 11 GPa corresponding to the phase transition to phase IV. At the same pressure, an Urbach tail responsible for the coloring of the solid H2S suddenly appeared. Raman signals excited with a green Ar ion laser (2.41 eV) were found to increase in intensity with pressure, which was explained by preresonance Raman effects induced by the decreasing of the gap energy near to the Raman excitation energy.

We have determined refractive indices of rubrene crystals in the wavelength regions where their emissions were observed. For this purpose, we grew in a vapor phase the rubrene crystals having both horizontal and vertical pairs of parallel crystal facets. The facets functioned as optical resonators that produced interference fringes in the emission and reflectance spectra. From the fringes in the emission spectrum, we estimated the dispersion of the phase refractive index along the crystal a-axis. The anisotropic group refractive indices were evaluated along the b-and c-axes from the fringes in the reflectance spectra. The experimental indices were compared with those computed from the density functional theory.

We have fabricated diffraction gratings of parylene by evaporation polymerization. The parylene film was deposited onto a commercially available diffraction grating used as a template and transfer-printed onto a substrate. A well-defined periodic structure was replicated on the parylene film surface and its period was in good agreement with that of the template. For future light-emitting device application, we laminated a parylene grating with organic semiconductor crystals and investigated their emission properties under weak ultraviolet light excitation. We observed emissions parallel to the grating wave vector. Their spectra narrowed as peaks with full-widths at half-maxima less than 5 nm. We discussed these narrow emission lines considering them as the propagating light in a waveguide composed of the organic crystal and parylene grating. The present results reflect the formation of a high-quality optical cavity on a parylene film.

We have improved the emission properties and the carrier mobilities of organic light-emitting field-effect transistors (OLEFETs) by modifying the metal electrode(s) with a thin film of n-type thiophene/phenylene co-oligomer (TPCO). Their semiconductor layer was a p-type TPCO crystal. When we used the modified electrode for electron injection, the device exhibited eight times higher emission intensity than a device with unmodified electrodes. By contrast, employing the modified electrode as the hole injection contact, we achieved the maximum hole mobility of 0.11 cm2·V-1·s-1 under the hole-enhancement mode. The modified electrodes effectively functioned for injecting both electrons and holes into the p-type crystal. The origin of this is briefly discussed.