The development of chelate metal complexes as an organicelectroluminescent material

The chelate metal complexes, such as tris(8-hydroxyquinolinate)aluminum (Alq₃), have excellent electroluminescent (EL) properties. Several chelate metal complexes were developed and the experimental rule of molecular design for use in an organic EL device was found. When the chelate metal complex has the structure of an inner complex sell, the EL device is fabricated by conventional vacuum-vapor deposition. This rule was applied to some chelate metal complexes, and, as a result, various complex materials could be obtained. RGB (red, green, and blue) emission was achieved using only chelate metal complexes, after successfully obtaining high-luminance blue-emitting materials, such as azomethine-zinc complex. This shows that the chelate metal complexes can be applied to full-color flat displays as an emitting material. As for durability, when Bis(10-hydroxybenzo[h]quinolinato)beryllium (BeBq₂) was used as an electron transport layer, a lifetime (initial luminance: 500 cd/m ²) of more than 3500 h, which is a practical level, was achieved in running tests. Thus, it seems that chelate metal complexes are a strong candidate as an organic EL material in practical use     

Analytical model for injection-controlled excimer laser amplifiers

A semiempirical model of a pulsed, injection-controlled laser is investigated analytically and is applied primarily to extensive experimental results that have been obtained for the XeF (C→A) excimer laser. The gain medium inside an unstable cavity is represented by a folded pulsed amplifier which is seeded by a narrowband input signal. A set of coupled rate equations for the population densities of the upper laser states, the wideband absorbers, and the photon flux was numerically integrated. Measured gain and absorption of the amplifier were used as input data to evaluate the model. Excellent agreement between calculated and experimentally observed peak intensity and various other pulse characteristics such as peak shape and laser pulse delay time was obtained. This model also predicts the experimentally determined injection-control threshold for KrF excimer lasers successfully, and should be applicable to numerous other injection seeded lasers     

Performance characteristics of an injection-controlledelectron-beam pumped XeF(C→A) laser system

Characteristics of an injection-controlled electron-beam pumped XeF(C→A) laser are investigated with emphasis on efficient wideband tuning and scaling issues. Using a quasi-CW dye laser as an injection source, data are obtained that describe the laser characteristics over a wide parameter range. A high-Z electron-beam backscattering reflector inside the laser reaction cell improved the electron-beam energy deposition by 40%, resulting in an increase of the amplified laser output by more than a factor of four. Efficient and continuous wavelength tuning between 470 and 500 nm is achieved with an output energy density of ~1 J/l, and an intrinsic efficiency of ~1% throughout the entire tuning region     

Tight inclusion of an acid guest into the cavity of cyclodextrin bearing an amino moiety in dimethyl sulfoxide

Circular dichroism measurements show that β-cyclodextrin with an amino moiety has a strong binding ability for ferrocenecarboxylic acid in dimethyl sulfoxide via an acid-base interaction.     

Influence of polyvinylalcohol on the solvation volumes of FeCl<Subscript>3</Subscript> and CoCl<Subscript>2</Subscript> in aqueous ethanol solutions

The effect of polyvinylalcohol (PVA) on molar, Van-der Waals and the electrostriction volumes of FeCl₃ and CoCl₂ in pure H₂O and 50% ethanol (EtOH)–water mixtures was studied. Excess volumes were also calculated and their values were discussed in terms of Pierotti theory (Scaled Particle Theory). Different theoretical energy values were calculated to explain the following parameters: volumes, dispersion, induction energies and 6-12 Lennard–Jones parameters. The increase and the decrease in excess volumes of FeCl₃, CoCl₂ in the absence and in the presence of polyvinyl alcohol in both aqueous and 50% EtOH–H₂O mixtures were also discussed in terms of the increase or decrease of different interaction energies.     

Electron transfer reaction in a single protein molecule observed by total internal reflection fluorescence microscopy

To observe an electron transfer (ET) process in a single protein molecule, we constructed a model system, Alexa-HCytb5, in which cytochrome b5 (Cytb5) is modified with a fluorescent probe, Alexa Fluor 647 dye. In this model system, intramolecular transfer of an electron from the Alexa dye to heme in Cytb5 is supposed to oxidize the probe and quench its fluorescence, and the ET reaction at the single-molecule level can be monitored as the intermittent change in the fluorescence intensity. Alexa-HCytb5 was fixed on the glass surface, and illumination of laser light by the total internal reflection resulted in blinking of the fluorescence from the single Alexa-HCytb5 molecule in the time scale of several hundred milliseconds. Each Alexa-HCytb5 molecule is characterized by its own rate constant of the blinking, corresponding to the ET rate constant at the single-molecule level, and its variation ranges between 1 and 10 s(-1). The current system thus enables us to visualize the ET reaction in the single protein molecule, and the protein ET reaction was found to be explained by the distribution of the rate constants. On the basis of the Marcus theory, we suggest that the origin of this rate distribution is the distance change associated with the structural fluctuation in the protein molecule.