Facile Oxidative Addition of O−H Bonds of Methanol and Water to IrI Complexes Having Peraryldiphosphane Ligands

A new piece in the puzzle. Hydrido(alkoxo) complexes of late transition metals have often been postulated as intermediates or transition states in the catalytic hydrogenation of carbonyl compounds and catalytic hydrogen transfer reactions. Here the facile oxidative addition of the O−H bonds of alcohol and water to iridium(I ) complexes of peraryldiphosphanes [Eq. (a)] is reported and the resulting complexes are described. R=H, Me.     

Oriented and low‐density tin dioxide film by sol–gel mineralizing tin‐contained hydroxypropyl cellulose lyotropic liquid crystal for laser‐induced extreme ultraviolet emission

A series of tin‐doped hydroxypropyl cellulose (HPC) lyotropic liquid crystal (LC) was synthesized using a simple process and their properties were characterized using selective reflection, wide‐angle X‐ray diffraction (WAXD), and the band texture observed under polarized optical microscope. The present preparation is applicable for mass production using large substrate with low cost HPC. A cholesteric lyotropic LC phase was observed for the hybrid solution with higher than 40 wt % HPC. After sol–gel condensation, the HPC‐Sn hybrid LC films were calcined at 400 °C and the as‐prepared product was determined to obtain tin dioxide (SnO₂) which was characterized using WAXD. The iridescent color and ～2 nm structure seen after the condensation disappeared in the as‐prepared SnO₂. Scanning electronic microscope images of the SnO₂ showed that the HPC content in the HPC‐Sn hybrid played an important role in controlling the SnO₂ morphology. A spectrum of relatively monochromatic extreme ultraviolet (13.5 nm) emission was measured in the as‐prepared SnO₂ in comparison with bulk tin and inverse opal SnO₂. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4566–4576, 2009     

Effective Raman gain characteristics in germanium- and fluorine-doped optical fibers

We describe the dopant dependence of Raman gain in germanium- and fluorine-doped optical fibers. We clarify, both theoretically and experimentally, the effective Raman gain characteristic in an optical fiber, which is closely related to the fiber's refractive-index profile and electromagnetic field profile. We also show that this experimentally determined relationship can be used to evaluate the effective Raman gain characteristic in a germaninum- or a fluorine-doped optical fiber with an arbitrary index profile.     

Long-scale jet formation with specularly reflected light in ultraintense laser-plasma interactions

Long-scale jetlike x-ray emission was observed in a 100-TW laser-plasma interaction. The jet was well collimated with a divergence of 30-40 mrad and continued from the target surface into underdense regions for a distance over 4 mm in the specular direction of the laser light. A two-dimensional particle-in-cell simulation shows an electron acceleration with the specularly reflected laser light and collimation of the electron stream by a self-generated magnetic field, resulting in the electron jet to the direction of the specularly reflected light.     

High-energy ion generation in interaction. of short laser pulse with high-density plasma

Multi-MeV ion production from the interaction of a short laser pulse with a high-density plasma, accompanied by an underdense preplasma, has been studied with a particle-in-cell simulation and good agreement is found with experiment. The mechanism primarily responsible for the acceleration of ions is identified. Comparison with experiments sheds light on the ion-energy dependence on laser intensity, preplasma scale length, and relative ion energies for a multi-species plasma. Two regimes of maximum ion-energy dependence on laser intensity, I, have been identified: subrelativistic, ∝I; and relativistic, ∝. Simulations show that the energy of the accelerated ions versus the preplasma scale length increases linearly and then saturates. In contrast, the ion energy decreases with the thickness of the solid-density plasma. Received: 13 December 2001 / Published online: 7 February 2002     

Proposed double-layer target for the generation of high-quality laser-accelerated ion beams

In order to achieve a high-quality, i.e., monoenergetic, intense ion beam, we propose the use of a double-layer target. The first layer, at the target front, consists of high-Z atoms, while the second (rear) layer is a thin coating of low-Z atoms. The generation of high-quality proton beams from the double-layer target, irradiated by an ultraintense laser pulse, is demonstrated with three-dimensional particle-in-cell simulations.     

Structure formation and tearing of an MeV cylindrical electron beam in a laser-produced plasma

The stability of a cylindrical, solid hot electron beam propagating in a high density plasma has been studied using a two-dimensional, hybrid Darwin code. The initially solid beam evolves into a hollow, annular beam due to the Weibel instability and generates strong magnetic fields on both sides of the annular ring. The annular structure subsequently breaks up into several beamlets via a mechanism similar to a tearing instability. It is found that the magnetic fields parallel to the direction of beam propagation also grow due to the tearing process.     

Selective H2 and CO production with rhenium(I) biscarbonyl complexes as photocatalyst

Rhenium(I) biscarbonyl complexes with two phosphine ligands photocatalyzed not only CO₂ reduction under CO₂ atmosphere but also H₂ evolution under Ar. The reductant 1-benzyl-1,4-dihydronicotinamide (BNAH) worked only as a one-electron donor, and it was quantitatively converted to its corresponding oxidized dimer (BNA₂). The photocatalytic reactions required addition of a base such as triethanolamine, because deprotonation from the oxidized BNAH (BNAH^?+) is essential for the suppression of the back electron transfer from the reduced rhenium(I) complex to BNAH^?+. ¹H, ¹³C, and ³¹P NMR studies under vacuum or ¹³CO₂ atmosphere indicated that the rhenium(I) complex is relatively stable under the CO₂ reduction conditions, but it is converted to some other complexes under the H₂ evolution conditions.     

Phase transitions of 6-(4-n-alkoxybenzoyloxy)-flavones and 3-cyano-7-(4-n-alkoxybenzoyloxy)-coumarins

Phase transitions of 6-(4-n-alkoxybenzoyloxy)-flavones (ABF) and 3-cyano-7-(4-n-alkoxybenzoyloxy)-coumarins (CABC) were studied using D.S.C. and polarized microscopy. ABF series showed a nematic phase which has an excellent thermal stability, whereas CABC series exhibited a smectic A phase in the longer 4-n-alkoxybenzoyloxy ones than 4-n-hexyloxybenzoyloxy. This difference in the mesogenicity was discussed from the structure and polarity of flavone and coumarin skeletons which may be associated with an intermolecular interaction in the mesophase.