摘要:

AbstractOrganised films containing oriented patches of purple membranes and consisting of 15–75 layers and approximately 1000 layers were fabricated by the Langmuir–Blodgett and electrophoretic sedimentation techniques respectively. ‘Surface pressure vs. molecular area’ isotherms for monolayers of purple membranes suspended in hexane and deposited on the air/water interface were studied. Circular dichroism and absorption spectroscopy were used to investigate the effect of an organic solvent on the chromophore binding site in the purple membranes. Kinetic methods based on flash excitation were employed to determine the influence of the film deposition conditions on the photoelectric response of bacteriorhodopsin and on the M412intermediate relaxation. Structural characteristics for multilayers prepared from water and hexane purple membrane suspensions were determined by low‐angle X‐ray scattering. The influence of the layer deposition conditions on the electrical, physical and photoelectrical properties of ordered structures containing bacteriorhodopsin i

ISSN:1057-9257    

DOI:10.1002/amo.860010302

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of chemically deposited SnS thin films to SnO2films by air annealing at temperatures up to 400°C is discussed. The conversion of a 0.7 μm thick SnS thin film to an SnO2film involves the creation of non‐stoichiometric SnS, SnS + SnS2mixed phase and non‐stoichiometric SnO2(i.e. SnO2  x), as concluded from X‐ray diffraction patterns, optical transmission spectra and electrical characteristics. The SnO2thin films obtained in this manner are photoconductive, with a lowest sheet resistance (in the dark) of about 105Ω/□ and an activation energy (Ea) of 0.1 eV for the electrical conductivity observed for the SnS films annealed at 325°C. This was found as the onset temperature for conversion of the SnS + SnS2phase to the non‐stoichiometric SnO2 – xfilm. Elevation of the annealing temperature to 400°C results in an elevation of the sheet resistance to about 109Ω/□ with the value ofEaat 1.3 eV, indicating an improvement in the de

ISSN:1057-9257    

DOI:10.1002/amo.860010303

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA new gas alarm is presented which is based on solid electrolytes with high ionic conductivities. The operating principle of the device is the compensation of the cell voltage and measurement of the direction of the electrical current. Also, the general microelectronic circuit designs are discussed. Several advantages are found in comparison with other types of gas sensors.

ISSN:1057-9257    

DOI:10.1002/amo.860010304

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA field effect transistor (FET) has been fabricated with the hexamer of thiophene (α‐sexithienyl) in order to assess the performance of such electronic devices based on an organic material. Particular emphasis has been given to the determination of the origin of the instability in the electrical performance. From this study it is confirmed that charged species, possibly chemical impurities present in the processed material, can migrate through the film under an applied electric field, even at room temperatu

ISSN:1057-9257    

DOI:10.1002/amo.860010305

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA new type of microelectrode array device has been developed using semiconductor‐processing techniques. An array of 15 × 15 square electrodes as small as 1 μm, spaced 100 μm apart, has been fabricated on a silicon chip of dimensions 1.5 × 1.5 mm2. Steady state electrochemistry was performed using these devices in both aqueous and non‐aqueou

ISSN:1057-9257    

DOI:10.1002/amo.860010306

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractMetal sulphide thin film (MSTF) photography based on photo‐accelerated chemical deposition (PACD) of PbS thin films is described. Here an intensity distribution over the surface of a growing PbS thin film produces a thickness variation (0.06–0.15 μm) of the film which, when viewed under daylight, yields a specularly reflective image. Under 800 W m−2of solar radiation a bluish MSTF photographic image (0.15 μm film thickness) on a coppery‐bronze background (0.08 μm) is obtained in the PACD of PbS at the end of 25 min deposition when a high‐contrast photographic negative is used as the object. The best contrast of 0.46 in the PbS MSTF photography in the reflection mode is obtained under the above condition of exposure when the optical transmission in a photographic negative in the image area is ∽30% and that in the background is ∽1%. The contrast available in the transmission mode in the MSTF photographic image is considerably less: ∽0.28 (maximum) for optical transmission of 1% and 100% in the background and image areas of the photographic neg

ISSN:1057-9257    

DOI:10.1002/amo.860010307

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractMolecular three‐centre electron transfer (ET) systems contain an intermediate electronic bridge group state in addition to the donor and acceptor states. This feature is encountered in long‐range ET patterns of metalloproteins, in bacterial photosynthetic reaction centres, in electrochemical processes at modified metal electrodes and in hypothetical or real molecular shift register and photodiode device‐like systems. Overall ET is by superexchange when the intermediate group energy is high. When the energy is low enough that the state is temporarily populated, a range of vibrational features arise depending on the vibrational coupling and relaxation time of the intermediate state. In external fields these properties induce characteristic ‘switch’ effects reflected in rapid changes in the current derivatives and other features in the current–voltage relations. We provide a quantum mechanical frame for three‐centre ET in such molecular systems. The theory rests on second‐order perturbation theory. In contrast to most applications of superexchange concepts, the theory includes explicitly nuclear coupling in the intermediate state and is valid both for high energy superexchange and for low‐energy populated intermediate states. Moreover, mild, finite resonances arise in the transition regions between the various energy ranges represented by analytical rate constants. The theory is appropriate to the molecular electronic behaviour of several biological and synthetic three‐level

ISSN:1057-9257    

DOI:10.1002/amo.860010308

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

ISSN:1057-9257    

DOI:10.1002/amo.860010301

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY