/pdf/self-assembled-monolayers-of-thiolates-on-metals-as-a-form-1neb0hj3k4.pdf

Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

The development of white organic light-emitting diodes (OLEDs) holds great promise for the production of highly efficient large-area light sources. High internal quantum efficiencies for the conversion of electrical energy to light have been realized. Nevertheless, the overall device power efficiencies are still considerably below the 60-70 lumens per watt of fluorescent tubes, which is the current benchmark for novel light sources. Although some reports about highly power-efficient white OLEDs exist, details about structure and the measurement conditions of these structures have not been fully disclosed: the highest power efficiency reported in the scientific literature is 44 lm W(-1) (ref. 7). Here we report an improved OLED structure which reaches fluorescent tube efficiency. By combining a carefully chosen emitter layer with high-refractive-index substrates, and using a periodic outcoupling structure, we achieve a device power efficiency of 90 lm W(-1) at 1,000 candelas per square metre. This efficiency has the potential to be raised to 124 lm W(-1) if the light outcoupling can be further improved. Besides approaching internal quantum efficiency values of one, we have also focused on reducing energetic and ohmic losses that occur during electron-photon conversion. We anticipate that our results will be a starting point for further research, leading to white OLEDs having efficiencies beyond 100 lm W(-1). This could make white-light OLEDs, with their soft area light and high colour-rendering qualities, the light sources of choice for the future.

White organic light-emitting diodes with fluorescent tube efficiency

The ability to control the size, shape, and material of a surface has reinvigorated the field of surface-enhanced Raman spectroscopy (SERS). Because excitation of the localized surface plasmon resonance of a nanostructured surface or nanoparticle lies at the heart of SERS, the ability to reliably control the surface characteristics has taken SERS from an interesting surface phenomenon to a rapidly developing analytical tool. This article first explains many fundamental features of SERS and then describes the use of nanosphere lithography for the fabrication of highly reproducible and robust SERS substrates. In particular, we review metal film over nanosphere surfaces as excellent candidates for several experiments that were once impossible with more primitive SERS substrates (e.g., metal island films). The article also describes progress in applying SERS to the detection of chemical warfare agents and several biological molecules.

Surface-Enhanced Raman Spectroscopy

Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

/pdf/lanthanide-luminescence-for-functional-materials-and-bio-1w9cppwf8r.pdf

Lanthanide luminescence for functional materials and bio-sciences

Surface-enhanced Raman spectroscopy.

A scanning near-field optical microscope (SNOM) combined with a scanning tunneling microscope (STM) is used to investigate nanoscopic optical phenomena both in the near-field region and in the proximity. The system is realized by introducing a doubly metal-coated optical fiber tip with an extremely small aperture, on which metal-coating is performed to obtain a half-transparent conducting tip. A simultaneous SNOM/STM observation is performed for an Au (111) surface, where the evanescent field standing on the tip vicinity through the aperture is scattered by the local structures of the sample and the far-field component of the scattered light is collected as an optical signal. The distance con-trol is carried out under constant current condition in order to separate the optical properties from surface topography. λ/100 optical resolution and the identical channel transport both for electrons and photons are achieved.

Development of a Hybrid Scanning Near-field Optical/Tunneling Microscope (SNOM/STM) System

主鎖にポリエン構造を有する種々の置換ポリアセチレンにイオン注入し, 構造変化に対する置換基の影響について検討した. 置換ポリアセチレンに, Na+, Ar+をイオン注入したところ導電率が上昇した. しかし, イオン種による差異がほとんど認められず, ドーピング効果に比べ注入イオンの運動エネルギーによる構造変化が支配的であった. イオン注入中の放出ガス中には試料の側鎖に起因する成分及び主鎖に起因する成分が見られた. また, イオン注入に対し安定な置換基, 不安定な置換基が存在した. イオン注入したポリ (1-クロロ-2-フェニルーアセチレン) では表面付近でCl原子の減少が見られ, 構造変化層はポリアセチレンに比べ非常に深い部分にまで達することが分かった. イオン注入による構造変化は側鎖の存在とその種類に大きく依存する. また, 置換基により電子が局在化した置換ポリアセチレンに対し, 長い共役系を持つポリアセチレンの主鎖は安定性が高い.

https://www.jstage.jst.go.jp/article/koron1974/44/4/44_4_259/_pdf

Structural changes of disubstituted polyacetylenes by ion implantation.

The polarization and depolarization behavior of electric field-induced polar alignment in a side- and main-chain photorefractive polymer was measured by thermally stimulated current (TSC) and electro-optic (EO) modulation experiments. A relaxation peak was observed around the glass transition temperature (Tg) for the poled photorefractive polymer in a TSC experiment. The apparent TSC was not observed at room temperature. The polarization calculated from the relaxation peak linearly increased with the strength of the poling electric field. This result was consistent with the EO behavior which showed the linear dependence of the EO coefficients on the poling electric field. The main- and side-chain photorefractive polymer could be aligned by the electric field at an elevated temperature, and the polar alignment was stable at room temperature, which could lead to the long-term stability of the photorefractive responses without an external applied electric field.

Hiroyuki Sasabe

Papers

Development of a Hybrid Scanning Near-field Optical/Tunneling Microscope (SNOM/STM) System

Structural changes of disubstituted polyacetylenes by ion implantation.

Thermally stimulated current and electro-optic responses in a main- and side-chain photorefractive polymer

THG in conjugated polymers and their application to optical waveguide

SEM Imaging of Single Heavy Meromyosin Molecules on Hydrophilic Silicon Surface