Square-Planar trans-Bis-(1-p-n-octylphenylbutane-1,3-dionato) copper (II), a New Compound Exhibiting Three Kinds of ‘Double Melting’ Behaviour

The new compound, bis-(1-p-n-octylphenylbutane-1,3-dionato) copper(II) has four polymorphs, C¹ (m.p. 96°C), all having the same squareplanar trans structure. C¹, C^a, and C^m exhibit ‘double melting’ behaviour, i.e., they melt at their was observed only on very rapid heating, while that of C^a and C^m only on slow heating. Slow solid-solid phase transition from C¹ to C^h was observed at ca 50°C. Each polymorph could be obtained as a stable form at room temperature and gave a quite different X-ray diffraction powder pattern. The interrelationships of the four forms have been clarified by differential scanning calorimetric and micriscopic measurements. When the melt of the complex is rapidly cooled, it converts into a glassy state, which is stable at room temperature. The glass transition temperature T₈ and the crystallizing temperature T_e are very close to each other at 52.5°C and 58.0°C, respectively.     

Chemical Far Infrared Spectroscopy

Abstract

A number of books, symposia, proceedings, special publications [1–9], and review papers in English covering catalytic surfaces [10, 11], solid surface characterization [12–191, thin film analysis [20–22], surface structure and bonding [23, 24], angular distribution of photoelectrons [25, 26], use of synchrotron radiation [27, 281, ion beam effects [29], different methods of surface study [30, 31], experimental and theoretical aspects of ultraviolet photoelectron spectroscopy (UPS) [32], and angle resolved UPS [33, 34] are available in literature. Reviews in other languages, namely Japanese [35–41], German [42–46], French [47–50], Italian [51], Russian [52], and Polish [53], are also available. But the present situation demands a thorough and up-to-date literature survey of the surface study by photoelectron spectroscopy in order to assess what has been done and what is left to be done. This paper is aimed at that goal.     

Self-Alignment of Optical Devices With Fiber for Low-Cost Optical Interconnect Modules

We propose a novel self-alignment process of optical devices with optical fiber. A vertical-cavity surface-emitting laser (VCSEL) was automatically coupled with a multimode fiber (MMF) through the surface tension of a liquid adhesive within 1.5 s. Misalignment between the center of the VCSEL and the fiber was measured to be 15 mum, which is acceptable for coupling the VCSEL with the MMF. High-speed pulse modulation of the self-aligned VCSEL up to 5 Gb/s, as well as at 1 Gb/s, was demonstrated. The average optical output power was as high as -5.9 dBm at 1 Gb/s.     

High optical coupling efficiency using 45 °-ended fibre for low-height and low-cost optical interconnect modules

High optical coupling efficiency of more than 80% between an optical fibre and a vertical-cavity surface-emitting laser (VCSEL) has been achieved without use of a lens. A 45deg-ended fine-drawn optical fibre can be positioned closer to a VCSEL than a conventional multimode fibre. 12.5 Gbit/s/ch optical signal transmissions using a low-height optical coupling structure have been demonstrated with optical output power as high as +2.0 dBm without use of a lens.     

Excess noise design of InP/GaInAsP/GaInAs avalanche photodiodes

An InP/GaInAsP/GaInAs avalanche photodiode (APD) with separate absorption and multiplication (SAM) regions has been designed taking into account the excess noise generated in GaInAsP and GaInAs. The multiplication factor dependence of the excess noise factorFhas been calculated using realistic electron and hole ionization rates in InP, GaInAsP, and GaInAs, assuming that the avalanche multiplication occurs not only in InP but in GaInAsP and GaInAs. The calculatedFvalues have been compared to the experimental ones measured on a planar-type InP/GaInAsP/GaInAs APD for illumination at a wavelength of 1.3 μm. It has been found the the calculated excess noise agrees very well with the experimental measurements. The limited ranges of device parameters in which the conditions of minimal excess noise, tunneling current, and charge pile-up are satisfied have been obtained. We conclude that the excess noise generated in GaInAsP and GaInAs should be considered in a practical device design.     

Electron and hole impact ionization rates in InP/Ga0.47In0.53As superlattice

The electron and hole impact ionization rates, α andβ, in an InP/Ga0.47In0.53As superlattice have been experimentally determined from photomultiplication data made on an InP/GaInAs superlattice photodiode. A Monte Carlo simulation of α and β in the superlattice has been developed, and the enhancement of impact ionization due to the effect of the band edge discontinuity has been investigated. The experimental ionization rates have been analyzed by the simulation. The larger β than α in the superlattice has been shown to be explained by the valence band discontinuity about two times larger than the conduction band edge discontinuity in this superlattice structure.     

Glass transition in charge carrier transport phenomena of amorphous photoconductive polymers

The critical temperature T_o in Gill's empirical equation for the charge carrier transport was found to have aclose connection with the glass transition temperature T_g for poly-N-vinylcarbazole containing model compound systems. Interpretations of T₀ and μ₀, i.e., the drift mobility at T₀, were presented.     

High-speed monolithic coherent optical receiver integrated on InP substrate

A monolithic coherent receiver have a directional waveguide coupler and a balanced pair of lateral pin photodiodes was fabricated. The lateral pin photodiode has an improved structure, exhibiting a 3 dB bandwidth of 2 GHz. Heterodyne detection with this monolithic receiver was demonstrated at 1.8 GHz and 2.3 GHz.<>     

Gain-bandwidth product of AlGaSb avalanche photodiodes analyzed byusing equivalent multiplication region method

An analysis presented for an AlGaSb diode in which it was approximated by a p-i-n diode with an equivalent multiplication region having a length of one-eighth of the whole depletion region and was combined with R.B. Emmon's p-i-n avalanche photodiode analysis (1967). A relationship between the gain-bandwidth product and the carrier concentration is derived, and it is shown to agree well with the experimental data