Ken Onda

At interfaces of metal oxide and water, partially hydrated or "wet-electron" states represent the lowest energy pathway for electron transfer. We studied the photoinduced electron transfer at the H2O/TiO2(110) interface by means of time-resolved two-photon photoemission spectroscopy and electronic structure theory. At approximately 1-monolayer coverage of water on partially hydroxylated TiO2 surfaces, we found an unoccupied electronic state 2.4 electron volts above the Fermi level. Density funct

Two-photon photoemission (2PP) spectra of $\mathrm{Ti}{\mathrm{O}}_{2}(110)$ surfaces are measured for the nearly perfect surface, and surfaces modified by introduction of defects and adsorbed molecules. Defects are generated on nearly perfect surfaces by three methods: electron irradiation, annealing in vacuum, and ${\mathrm{Ar}}^{+}$ sputtering. Nearly perfect or damaged surfaces can be further modified by adsorption of ${\mathrm{O}}_{2}$ or ${\mathrm{H}}_{2}\mathrm{O}$ molecules. 2PP spectros

The quasistable state in the photoinduced phase transition for the quasi-one-dimensional quarter-filled organic conductor (EDO-TTF)2PF6 has been examined by ultrafast reflective measurements and time-dependent model calculations incorporating both electron-electron and electron-phonon interactions. The transient optical conductivity spectrum over a wide probe photon-energy range revealed that photoexcitation induced a new type of charge-disproportionate state. Additionally, coherent and incohere

The photochemistry of fac-[Re(bpy)(CO)(3)Cl] (1 a; bpy=2,2'-bipyridine) initiated by irradiation using <330 nm light has been investigated. Isomerization proceeded in THF to give the corresponding mer-isomer 1 b. However, in the presence of a small amount of MeCN, the main product was the CO-ligand-substituted complex (OC-6-24)-[Re(bpy)(CO)(2) Cl(MeCN)] (2 c; bpy=2,2'-bipyridine). In MeCN, two isomers, 2 c and its (OC-6-34) form (2 a), were produced. Only 2 c thermally isomerized to produce the

Abstract [Ru(bpy) 3 ] 2+ is well‐known as a prototype for the Ru(II) complexes used in a wide variety of photofunctional materials. The triplet metal‐centered ( 3 MC) state is important in this complex, since it dominates the phosphorescence lifetime and photoreaction processes. Despite this, the 3 MC state has not yet been observed by spectroscopic methods. In the present study, we demonstrated that time‐resolved infrared vibrational spectroscopy enables observations of the 3 MC state. A vibrat

The supramolecular photocatalysts in which a Ru(II) complex as a molecular redox photosensitizer unit and a Re(I) complex as a molecular catalyst unit are connected with a various alkyl or ether chain have attracted attention because they can efficiently photocatalyze CO₂ reduction with high durability and high selectivity of CO formation, especially on various solid materials such as semiconductor electrodes and mesoporous organosilica. The intramolecular electron transfer from the o

The optical–optical double resonance (OODR) spectra of Rydberg 3Σ+ states of Hg(n3S1)Ne (n=8–10) and Hg(83S1)Ar were measured by using A and B states as intermediate states in the OODR process. The interatomic potentials of three states of HgNe and one state of HgAr were determined over a wide range of interatomic distance, R=3–7 Å, by the analysis of the vibrational structure of their OODR spectra. It was found that the potential shape varies sensitively with n and converges to that of the ion

A two-dimensional nanocarbon, graphene, has attracted substantial interest due to its excellent properties. The reduction of graphene oxide (GO) has been investigated for the mass production of graphene used in practical applications. Different reduction processes produce different properties in graphene, affecting the performance of the final materials or devices. Therefore, an understanding of the mechanisms of GO reduction is important for controlling the properties of functional two-dimensio

Supramolecular photocatalysts comprising [Ru(diimine)₃]²⁺ photosensitiser and <i>fac</i>-[Re(diimine)(CO)₃{OC(O)OC₂H₄NR₂}] catalyst units can be used to reduce CO₂ to CO with high selectivity, durability and efficiency. In the presence of triethanolamine, the Re catalyst unit efficiently takes up CO₂ to form a carbonate ester complex, and then direct photocatalytic reduction of a low concentration of CO<sub>2

Abstract The electronic structure and photophysics of the recently designed organic direct singlet harvesting (DSH) molecule are explored, in which donor (D) and acceptor (A) are held at distance by two bridges. One of the bridges is functionalized with fluorene. This structure leads to an ultrasmall singlet–triplet energy gap of ∆ E ( S 1 − T 1 ) ≈ 10 cm −1 (≈1 meV) between the charge transfer states 1,3 CT and shows an energetically close‐lying 3 ππ * state localized on fluorene. Dielectric co

CONSPECTUS: Phenomena that occur in nonequilibrium states created by photoexcitation differ qualitatively from those that occur at thermal equilibrium, and various physical theories developed for thermal equilibrium states can hardly be applied to such phenomena. Recently it has been realized that understanding phenomena in nonequilibrium states in solids is important for photoenergy usage and ultrafast computing. Consequently, much effort has been devoted to revealing such phenomena by developi

The interatomic potentials of the singlet Rydberg series of the HgNe dimer 1Σ+ Hg(n1S0)Ne (n=7–9) were determined over a wide range of interatomic distance by the analysis of the optical–optical double resonance (OODR) spectra measured in the present study via the A 3Π0+ and B 3Π1 states. The interatomic potential for n=7 consists of one bound vibrational level (v=0), three quasibound levels (v=1–3) trapped inside a potential barrier, and one weakly trapped quasibound level just above the potent