摘要:

Diffuse reflection spectra are measured for (PbI2)5clusters incorporated into supercages of zeolite LTA crystals, where the Frenkel exciton of cluster crystal is expected to be realized. The reflectivity at the exciton resonance energy drastically increases as the loading density nears the saturation level. This result can not be interpreted by the increase of the cluster density, but by the cluster ordering. We propose the order-induced decrease in the damping energy of the Frenkel exciton, because the motional narrowing of the exciton is expected in the ordered (PbI2)5clusters. Electron diffraction pattern shows that clusters are arrayed in twice period of the zeolite cages.

ISSN:1058-725X    

DOI:10.1080/10587259208047016

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Luminescence decay time and quantum yield of a pyrene single crystal are observed by a pulse method between 40-300 k. The temperature dependence on the intrinsic life time of emissions shows a peculiar character. The abrupt change of the analyzed intrinsic life time corresponds to the critical temperature of the phase transition. The mechanism of the phase transition is attributed to the formation of the trapped excimer excitons which deform the lattice around them. Further, the phase transition is concluded as the first kind type.

ISSN:1058-725X    

DOI:10.1080/10587259208047017

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The formation of mixed molecular layers is technologically important but the understanding of such molecular systems is limited. The comparative analysis of photoemission experimental results near threshold from organic dye layers, both in pure form and with a second kind of molecules present, shows that the energy levels of the dye molecules are affected by the presence of the foreign species. A theoretical model is presented for the calculation of the observed shift of the energy levels from Coulomb interactions in mixed aggregates and the results are applied to the study of the mechanism of supersensitization.

ISSN:1058-725X    

DOI:10.1080/10587259208047018

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

For potential applications of organic materials as active components In electronics, the energetic position of their valence and conduction levels are important parameters. For a given parent molecule, e.g. an aromatic hydrocarbon, the positions of these levels can be shifted substantially by attaching donor- or acceptor-type side group units. This will be demonstrated for the perylene skeleton in perylene-3,4,9,10-tetra-carboxylic-dianhydride. N,N′-diphenyl-perylene-3,4,9,10-tetracarboxylic-diimide, and diindeno[1,2,3.-c,d:1′,2′,3′-Imlperylene. Energy level manipulation by introducing donor: acceptor ground state interactions is another possible concept which has been checked withsingle crystalsof the stoichiometric donor: acceptor complexes tetrathiafulvalene: p-chloranil, phenothiazine: tetracyanoquinodimethane. phenothazine: pyromellitic-dianhydride, perylene: pyromellitic-dianhydride and perylene: tetracyanoquinodimethane. where a certain dark conductivity or light-induced photoconductivity served to eliminate charging problems.

ISSN:1058-725X    

DOI:10.1080/10587259208047019

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Photopolymerization process was studied by UV photoelectron spectroscopy (UPS) and X-ray absorption near edge (XANES) spectroscopy for long-chain diacetylene tricosa-10,12-diynoic acid and its Cd salt in the form of oriented evaporated films and Langmuir-Blodgett films, respectively. The UPS results revealed a large reduction of ionization energy due to the pi-band formation. The XANES fesults also showed spectral changes caused by the formation of π* band.

ISSN:1058-725X    

DOI:10.1080/10587259208047020

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Excitonic photoemission has been studied in aromatic hydrocarbon crystals (anthracene, naphthacene, α- perylene and p-terphenyl). Two mechanisms could be identified: (1) singlet exciton annihilation S1+ S1→ e-and (2) photoionization of singlet exciton S1+ hμ → e-.

ISSN:1058-725X    

DOI:10.1080/10587259208047021

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In the pressure-induced orientationally disordered phase of H2S (P = 0.47 ∼ 11 GPa), the dynamics of hydrogen bonds is investigated by the pressure dependence of Raman frequencies. The following process repeats; molecular rotation → hydrogen-bonds formation → μ1oscillations → hydrogen-bonds breaking → molecular reorientation.

ISSN:1058-725X    

DOI:10.1080/10587259208047022

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

New method is suggested and applied for an estimation of the delocalization length of charge carriers in photoconductive polymers based on the magnetic field effect (MFE) on the photoconductivity (PC). The method was applied to photoconductive polymers PTS, PPV, PPPV, DMOP-PPV and has permitted to estimate delocalization lengths as large as 60 Å. It makes questionable the usage of Onsager's model of charge separation for conjugated polymers (CP).

ISSN:1058-725X    

DOI:10.1080/10587259208047023

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Ionidy charged olefins intercalated in the interlayers of clay minerals are subject to photocyclodimerization with quite high efficiencies and regioselectivities. These product selctivities can be used to study molecular aggregate structure in an assistance with their fluorescence properties.

ISSN:1058-725X    

DOI:10.1080/10587259208047024

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Photogeneration of nonlinear excitations in the six thiophene unit oligomer of polythiophene has been studied. The formation of polarons is inferred from the observation of IRAV modes associated with midap electronic transitions confirming the theoretical expectations that these electronic excitations are stable in short oligomers.

ISSN:1058-725X    

DOI:10.1080/10587259208047025

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor