Optical characteristics of one-dimensional photonic crystals composed of high-aspect-ratio Si walls fabricated on V-grooved wafer

We demonstrate optical properties of one-dimensional photonic crystals (PC), which are fabricated using high-aspect-ratio etching on a V-grooved silicon wafer. The measured transmission spectrum has an obvious band gap; the suppression is over 30 dB. The quite small insertion loss of 1.9 dB is achieved by induced coupled plasma (ICP) cryogenic etching and direct coupling to the optical fiber aligned in the V-groove. We also successfully observed peaks originating from a localized cavity mode. Such a microcavity enables control of the light, which qualifies photonic crystal as a fundamental structure of optical functional devices. These results lead to achievement of integrated Si-based photonic circuits.     

Copper(II) chloride as a new,efficient additive suppressing racemization in peptide synthesis by the carbodiimide method

Copper(II) chloride was found to be an extremely efficient additive suppressing racemization in the carbodiimide mediated couplings.     

Radical formation during tensile deformation of highly drawn crystalline poly[p-(2-hydroxyethoxy)benzoic acid] fibers

The micromechanism of tensile deformation of poly[p-(2-hydroxyethoxy)benzoic acid] fibers is discussed on the basis of a detailed esr study of radical formation. The concentration of primary phenoxy radicals, which were detected during deformation at room temperature as a direct indicator of main-chain rupture, was determined by extrapolating the radical decay curves at various strains to zero time. The relation between the initial radical concentration and the strain is well expressed by the cumulative normal distribution curve. By use of this relation and a model of fiber structure, the distribution of the contour length of tie chains was determined. No radicals were detected during a second stretching cycle until the maximum strain in the first run was exceeded. The deformation model which includes alternating crystalline and amorphous regions connected by tie chains, a distribution of contour lengths of tie chains, and a phase transformation of molecular chains in the crystalline region accounted fairly well for the observed stress–strain behavior of monofilaments in first and second stretching cycles. The comparison between the observed and the calculated radical concentration suggests that statistical factors and other deformation mechanisms have to be taken into account.     

Accessibility of Ion-Ion Hybrid Resonance

The dispersion relation for the ion-ion hybrid resonance has been investigated in the density region of 106 cm-3 to 1017 cm-3 with the parallel wave number as the parameter, and the accessibility condition is presented.