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The kinetics of dye adsorption onto a mesoporous TiO2 film is compared between Ru(II) complex dyes with and without carboxy groups in the bipyridyl ligand, by diffuse reflectance spectroscopy at room temperature. Both dyes show adsorption saturation, and the dye without carboxy groups simply obeys the Langmuir isotherm equation. The dye with carboxy groups exhibits the same kinetics as the dye without carboxy groups in the period up to 20 min. However, in contrast to the latter, it increases its adsorption rate after this time, suggesting a change of the adsorption mode from physisorption to chemisorption. The carboxy group in the dye-sensitized solar cell is assumed to play a role in the chemical modification of the TiO2 surface via a two-step adsorption from physisorption to chemisorption.

The absorption edges of five periods of In x Ga 1Àx N (3 nm)/GaN (15 nm) (x ¼ 0:07 { 0:23) quantum wells (QWs) are characterized by photoacoustic (PA) measurement at room temperature. The absorption edge is determined by differentiating the PA signal curve to obtain the inflection point on the assumption that the signal curve consists of Urbach tail in the lowenergy region and Elliott's equation in the high-energy region. The constant absorption edge of GaN is observed at 3.4 eV and an absorption edge redshift with increasing In composition is observed for InGaN QWs. As a result, the Stokes shift increases with In composition and the highest shift of 435 meV is observed at x ¼ 0:23. From the energy calculation of optical transition in the InGaN/GaN QWs under an internal polarization field, the transition between the ground states confined in the well with a triangular potential causes a low-energy shift in the photoluminescence peak from the bulk band-gap energy, and the excited bound states whose wave functions are confined by the step-linear potential extending over the GaN barrier lead to the highenergy shift in the absorption edge.

A super configuration–interaction method is applied to a direct calculation of orthogonal localized molecular orbitals (LMO). Its iterative procedure converges quadratically, retaining the initial forms of the LMOs. When the basis sets of large sizes are employed for the calculation, Davidson’s diagonalization method can be adopted beneficially, where the time-consuming four-index transformation of LMO integrals is replaced by simpler two-index transformations. Test calculations using double-zeta basis sets are reported in detail for H2CO (formaldehyde). B2H6 (diborane), C3H4(1-propyne [metylacetylene]), and cytosine. The implication of the method concerning macromolecular calculations is discussed.