摘要:

AbstractAt 150 K [Ba(TDFND)2, tetraglyme] crystallises in theP1/cspace group witha= 17.15(2) Åb= 10.735(5) Å,c= 22.830(7) A, β = 97.56 (7)°,V= 4165 (5) Å3,Z=4.R1= 0.0435,wR2= 0.1079. The barium atom is nine‐co‐ordinate, with binding to all the O atoms. The two BaTDFND rings are planar but tilted by 26° from being co‐planar. The five O atoms of the tetraglyme ligand are also essentially co‐planar, but this plane subtends angles of 88.8(1)° and 67.4(1)° to the two BaTDFND planes. The BaO (TDFND) bond lengths are longer than for other related compounds, but the BaO (tetraglyme) bond lengths are similar to those in [Ba(HFA)2.tetraglyme] (HFA  CF3C(O)CHC(O)CF3). The low melting point and the fact that [Ba(TDFND)2.tetraglyme], alone of barium complexes of this kind, can be evaporated without decomposition at 1 atm are attributed to lower intermolecular forces for this compound and to its grea

ISSN:1057-9257    

DOI:10.1002/amo.860050103

出版商:John Wiley&Sons Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe growth modes of CdS thin films on glass in a chemical bath were analysed using scanning electron microscopy and optical microscopy. The results of these studies show that the film growth occurs by ion‐by‐ion condensation and by colloidal particles of CdS adhering to the substrate. Both mechanisms are operative from the initial stages of film growth. The predominance of one or other of these two growth modes depends on the abundance of Cd and S ions present in the solution, which is determined by the amount of complexing and sulphurising agents and ammonia used for the controlled release of Cd and S ions into the solution. The growth mode influences the optical properties of the fi

ISSN:1057-9257    

DOI:10.1002/amo.860050104

出版商:John Wiley&Sons Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractLaser‐induced TiCl4decomposition at vapour pressure was performed and comparative study of the composition and structure of thermally (at 10.6 μm) and photolytically (at 248 nm) deposited Ti‐based films is presented. Emphasis was given to the less explored titanium deposition process by CO2laser pyrolysis of TiCl4. The detailed structure of films deposited on quartz substrates was examined by scanning electron microscopy and X‐ray photoelectron spectroscopy. The influence of the incident laser energy on the chemical content of the films as well as on the film growth rate was demonstrated. The results indicate that in the thermal IR decomposition of TiCl4a multilayer structure is formed with unsaturated TiSixat the interface and oxidized phases at the surface. The photolytic process leads to films with increased purity and a specific growth morp

ISSN:1057-9257    

DOI:10.1002/amo.860050105

出版商:John Wiley&Sons Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractQuinizarin (1,4‐DHAQ) and Ag/I,4‐DHAQ thin films deposited under vacuum were investigated byI–Vmeasurements at various temperatures. It is shown that when submitted to an electric field of 5 × 105V cm−1or less, theI‐Vcharacteristics of AI/DHAQ/AI sandwich structures are ohmic. The temperature dependence isI∝ exp(‐ΔE/kT). The measured activation energy is 0.3 eV in the case of pure DHAQ and 30meV in the case of Ag/DHAQ. Therefore we can imagine that in the former case the conductivity is controlled by thermally activated hopping above intermolecular barriers, while in the latter case the conductivity can be attributed to tunnelling betwee

ISSN:1057-9257    

DOI:10.1002/amo.860050106

出版商:John Wiley&Sons Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractSpiropyran SP1822 J‐aggregate LB films show a non‐linear photochromic response with a threshold against the incident light intensity of a CW dye laser. Using two laser beams operating below the threshold level intensity, the logic ‘AND’ function was found to be optically stored as an overlapping region of two incident patterns. We proposed the adoption of an LB film of spiropyran J‐aggregates to store the memory matrix Tijklas an overlapping region of learning input pattern Vijand multi‐image input pattern Vklin order to construct an optical neural network system based on Hop

ISSN:1057-9257    

DOI:10.1002/amo.860050107

出版商:John Wiley&Sons Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe development of low‐loss fluoride glass fibres for transoceanic telecommunications led to an increased demand for inorganic fluorides with ultrahigh purity in respect of transition metals, rare earths and oxygen. This review paper describes the Merck Ltd strategy for achieving a wide range of metallic fluorides using methods of preparation and purification selected for a combination of technical efficacy and economic practicability. General preparative methods involving aqueous and non‐aqueous routes are described, together with purification methods such as ion exchange, zone refining and vacuum sublimation. The special role of ammonium fluoride complexes is discussed. The application of these general methods to the manufacture of fluoride glass components is described, with special reference to the ZBLAN formulation. Additional glass compositions and their individual requirements are also discussed. The parallel application of high‐purity metal fluorides in the growth of optical crystals is emphasised, the history of fluoride ultrapurification having begun with the early demand for high‐quality UV and IR crystals such as CaF2

ISSN:1057-9257    

DOI:10.1002/amo.860050108

出版商:John Wiley&Sons Ltd.    

年代:1995

数据来源: WILEY

ISSN:1057-9257    

DOI:10.1002/amo.860050102

出版商:John Wiley&Sons Ltd.    

年代:1995

数据来源: WILEY