NMR study of the self-induced vortex in (Ce1−xGdx)Ru2

NMR measurement of ¹⁵⁷Gd has been performed in zero external field in (Ce_1?xGd_x)Ru₂ for x = 0.100and 0.119 at low temperature down to 25 mK. Zero field NMR is observed with large enhancements both of H₁ and the intensity of the signal that are characteristic in ferromagnet. T₁T increases rapidly with decreasing temperature, which is attributed to the appearance of the superconducting energy gap whose magnitude is estimated to be 0.066kT_Cforx = 0.100. The NMR intensity in the superconducting state decreases not so drastically as expected in the perfect Meissner state. These results are qualitatively the same as reported previously for x ≥ 0.105 and T ≥ 60 mK. The results suggest that the system is in the state of self-induced vortices predicted theoretically.     

Anisotropic optical properties of pure and doped polyacetylene

Optical absorption and reflection measurements have been carried out on pure and doped polyacetylene films. The absorption data are consistent with a model of (CH)_X as a direct gap quasi-l d semiconductor; doping with AsF₅ or iodine introduces absorption within the gap, but appears to leave the interband transition intact. The anisotropic reflectance from partially aligned films and the increased optical anisotropy upon doping provide evidence of quasi-l d behavior of the semiconducting pure polymer and the metallic doped polymer.     

The light acceptance angle of a graded index fibre

The acceptance angle of a graded index fibre, which corresponds to the numerical aperture, is presented. A geometrical technique is used to obtain the exact ray trajectory of the beam propagating along the fibre. The acceptance angle in a conventional multimode fibre is not influenced by the position in the fibre cross-sectional area, especially for the meridional rays. However in a graded index fibre, it is a function of position on the cross section of the fibre and of the incident angle of the beam. As the position moves into the fibre periphery, the acceptance angle decreases monotonically and approaches zero.     

Copolymerization of propylene with acrylate by a Ziegler-Natta type catalyst

Propylene was polymerized by using a Ziegler-Natta type catalyst in the presence of ethylchloroaluminum acrylate, which was formed by the reaction of diethylaluminum chloride with acrylic acid. The polymer obtained contained acrylic units which were proved to be copolymerized with propylene units by solvent extraction, infrared spectrum, and NMR spectrum. The copolymer showed much improved properties compared with the polypropylene homopolymer.     

Microwave spectrum of monodeuterated diacetylene due to vibrationally induced dipole moment

Microwave spectrum of monodeuterated diacetylene (HCCCCD), which is nonpolar in the equilibrium configuration, was observed in various excited states of bending vibrations. Dipole moments in the ν₆, 2ν₆, and ν₆ + ν₉ vibrational states were determined from the Stark effect measurement to be 0.0907(6), 0.1681(14), and 0.0900(4) D with uncertainties in parentheses, where ν₆ and ν₉ denote respectively the CCH bending and lowest frequency bending vibrations. The l-type doubling constant in the ν₆ state is 2.1316(28) MHz. Rotational constants were determined in MHz; ν₆(Π), 4086.2165(44); 2ν₆(Δ), 4087.6963(58); ν₆ + ν₉(Δ), 4097.7537(50); 2ν₈(Δ), 4094.4786(103); ν₆ + ν₇(Δ), 4092.9074(176); ν₇ + ν₈(Δ), 4095.8925(354); 2ν₆ + ν₉(Φ), 4098.9505(339).     

10-Gbit/s Serial Optical Interconnection for an ATM Switch

Serial optical interconnection is proposed for connections in a Torus asynchronous transfer mode switch. A cross-point switch was developed that operates at a bit rate of 20 Gbit/s. The switching operation was successfully performed using cascaded cross-point switches through an optical interconnection configuration consisting of commercial optoelectronics devices. The measured switching rate was 10 Gbit/s, and it was limited by the responses of the optoelectronics devices.