摘要:

We utilized the first metathesis reaction to synthesize a new type of photorefractive polymers that contain both a carbazole moiety as a hole transporter and NLO chromophores, attached to π-conjugated backbones. These polymers show two maximum values of photocurrent around 350 and 700nm.The electro-optic coefficient (r33) of the poled polymer films measured at the wavelength of 1.3 μmwas in the value of 10.1pm/V. The nonresonat values of the third-order NLO coefficient, χ(3), of the resulting polymers were found to be 2.9 × 10−32esu.at the incident wavelength of 1.907 μm.

ISSN:1058-725X    

DOI:10.1080/10587259808044467

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We have synthesized two classes of polyureas withmono- anddiazoaromatic groups in their main chains. Holographic gratings were fabricated on the polyurea films prepared by spin-coating from solutions. Regularly spaced surface relief gratings on the polymer film were also recorded upon exposure to an interference pattern of two polarized argon laser beams.

ISSN:1058-725X    

DOI:10.1080/10587259808044468

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The crosslinkable polymer matrices and NLO chromophores containing alkoxysilyl groups are used in this system to increase the stability of NLO property for sustaining photorefractive effect. The polymer systems with or without crosslinkable groups were prepared from PMMA, poly(MMA-co-TMSM), poly(VK-co-MMA) and poly(VK-co-TMSM) doped with modified DR1 (DRS) and modified carbazole (CzS). The photoconductivity and second harmonic generation measurements for poled thin films were carried out to manifest the photorefractive effect. The d33values were high (about 40 pm/V) and the temporal stability for crosslinkable polymer system was reasonably high (without UV-absorption change for 90 hrs). The electric field dependence of the photoconductivity was obtained by negative discharging method. Furthermore, photorefractivity was confirmed from two-beam coupling (2BC) measurements. It follows a value of the normalized gain coefficient1′ of 2∼13cm−1at 633nm.

ISSN:1058-725X    

DOI:10.1080/10587259808044469

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We report on the fabrication and characterization of electroluminescent devices based on a thin film preparation strategy that involves the alternate polyelectrolyte deposition from aqueous solution for the hole injection/transporting layer combined with a conventional spin-cast method for the luminescent layer (MEH-PPV). Surface plasmon optical techniques are used to monitor the deposition process in-situ, as well as to quantify structural parameters of the final multilayer assemblies. These data are complemented by UV-vis spectroscopy, and X-ray reflectivity measurements. The final devices are functionally characterized in terms of their current-voltage, as well as their luminance-voltage performance.

ISSN:1058-725X    

DOI:10.1080/10587259808044470

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

J-aggregation of cyanine molecules was induced in two types of mixed LB films by the photoisomerization of azobenzene coexisting in the same LB films. Drastic morphological changes involving the formation of three-dimensional cone-shaped structures protruding from the film surfaces were observed accompanied with the J-aggregation. This means that the two-dimensional LB film structures exerted substantial modification by the photoisomerization.

ISSN:1058-725X    

DOI:10.1080/10587259808044471

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Silica films doped with water soluble porphyrin, 5,10,15,20-tetrakis[4-(N-trimethyl)ammonio]phenylporphyrin (TTMAPP), were deposited on the surface of a glass slide at 25–35°C by the liquid phase deposition (LPD) method from saturated hydrofluorosilicic acid or fluorosilicate solutions containing TTMAPP. It was doped as protonated (cationic) or neutral forms depending on the deposition condition. Two forms are reversibly converted by heat treatment or environments. The lifetime of excited triplet state of TTMAPP in silica films was more than ten times longer than that in aqueous solutions used for deposition. Fairly strong molecular interaction of excited triplet states in aqueous solutions was almost eliminated in silica films. The LPD method is useful to fix firmly organic dyes in silica at high concentrations without undesirable molecular interactions.

ISSN:1058-725X    

DOI:10.1080/10587259808044472

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Elastomeric poly(dimethylsiloxane) (PDMS) stamps were used for micro-contact printing (μ-CP) to pattern the adsorption of alkanethiolates on surfaces of gold on a scale of submicron. With this printing, organic surfaces patterned with well-defined regions exhibiting different chemical and physical properties have been produced. Au-coated mica substrates were treated with functionalized thiols to produce self-assembled monolayer (SAM) surfaces terminating with Br and OH groups by μ-CP method. Lateral force microscopy (LFM) has been utilized to characterize the adhesive interactions between substrates and probe tips that had been functionalized with SAMs which terminate with Br and COOH groups, respectively. LFM data exhibit that friction force between the probe tip and sample surfaces strongly depends on the functionality of both surfaces. This approach can be served as a method for mapping more complex and chemically heterogeneous surfaces.

ISSN:1058-725X    

DOI:10.1080/10587259808044473

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Dibis(ethyleneditho)tetrathiafulvalene (BEDT-TTF) was vacuum-deposited onto KC1 {001} and mica {001}. The molecular orientation in thin films and surface morphology were characterized using transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). On the KC1 substrates, BEDT-TTF crystals were oriented epitaxially in the relation of (10–2) [020]BEDT-TTF//(001)[001]KC1± 5° Two types of orientations were found in the films on the mica substrates Coexisting with the orientation found in the films on KC1, (2–21)BEDT-TTF//(001)micawas found in the films formed on the mica substrate. However, the two-dimensional epitaxial relationship was not observed in the BEDT-TTF films formed on the mica surface.

ISSN:1058-725X    

DOI:10.1080/10587259808044474

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Oriented purple membranes produce the transient photoelectric signal when irradiated by a pulsed light. This photoelectric signal contains three main components(each called B1, B2, and B3) with different lifetimes ranging from picosecond to millisecond. B1 and B2 are the internal vectorial components since the reflection of the inner charge change of the membrane. Therefore, the direction of B1 and B2 depends on the orientation of purple membrane in the film. However, B3 is not the vectorial components because the direction of B3 does not depend on the orientation of purple membrane in the film but depends on the pH of the film modified electrode in electrolyte solution.

ISSN:1058-725X    

DOI:10.1080/10587259808044475

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Thermal phase transitions of a cast film of an imidazole-containing amphiphile on a quartz crystal were monitored by the in situ measurement of the resonant frequency and the resonant resistance together with differential scanning calorimetry. The change of phase transition behaviors with scanning times could be confirmed by using the resonant resistance technique which was much more sensitive to the viscoelastic phase transitions than was the change of the resonant frequency.

ISSN:1058-725X    

DOI:10.1080/10587259808044476

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor