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Volume 70, Issue 5
Displaying 1-6 of 6 articles from this issue
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Hiroshi SEGAWA, Masaki SAKAI, Yonbon ARAI, Jotaro NAKAZAKI2007 Volume 70 Issue 5 Pages 260-267
Published: October 25, 2007
Released on J-STAGE: February 17, 2011
JOURNAL FREE ACCESSPhoto-functionality of self-organized nano-scale molecular systems is very attractive and important target. In this study, films of water-insoluble porphyrin J-aggregates were prepared by LB technique. At the air-water interface, J-aggregates of T (4-MeOP) P formed highly oriented monolayer, in which porphyrin macrocycles are aligned perpendicular to the substrate. The monolayers could be built up to multi-layers until 20 layers without structural disorder in each layer. Similar multi-layered assemblies of two-types of porphyrins with different substituents were constructed and excitation energy transfer between the layers was observed. In the case of water-soluble porphyrins, novel J-aggregates of TSThP isomers were found to show various self-organizing behaviors. For the typical TSPP J-aggregates, it proved that the aggregates show reversible redox process and form stable π-radicals through photochemical process for the first time. These results would be useful for fundamental studies of radicals of porphyrin J-aggregates and application as novel photo-electronic materials.View full abstractDownload PDF (3812K) -
Jin MIZUGUCHI2007 Volume 70 Issue 5 Pages 268-277
Published: October 25, 2007
Released on J-STAGE: February 17, 2011
JOURNAL FREE ACCESSInteractions between excited molecules will prevail in organic crystals or aggregates, provided that the absorption coefficient of the component molecule is high and they are arranged periodically. This phenomenon is called excitonic interactions (i. e. interactions between transition dipoles) observed often in dyestuffs and pigments that induces spectral shifts or band splitting (Davydov splitting). The present paper describes an overview of the exciton theory and presents some examples which include J-aggregates of cyanine dyestuffs.View full abstractDownload PDF (1435K) -
Makoto FURUKI2007 Volume 70 Issue 5 Pages 278-286
Published: October 25, 2007
Released on J-STAGE: February 17, 2011
JOURNAL FREE ACCESSWe studied formation of J aggregates on squarylium dye with four alkyl substituent groups. Using mono-molecular layer at air-water interface, structures of dye molecules for formation of J aggregates were clarified. The mono-molecular layer of J aggregates advantageous to evaluate its functions quantitatively because of the ideally two-dimensional structure. We investigated characteristics of the J aggregate such as strong interaction with light at resonant wavelength and typical delocalization of the excited state using this squarylium dye J aggregates.View full abstractDownload PDF (2028K) -
Tadaaki TANI2007 Volume 70 Issue 5 Pages 287-294
Published: October 25, 2007
Released on J-STAGE: February 17, 2011
JOURNAL FREE ACCESSIn color films, which represent silver halide (AgX) photographic products, the components of three primary colors in an incident light image are captured in the corresponding three separate layers owing to the absorption of incident photons by sensitizing dye molecules on AgX grains. A photo-excited state of a dye molecule is regarded as an exciton, which migrates, and dissociates to inject an electron into the conduction band of an AgX grain, leaving a positive hole in dye phase (i. e., a dye positive hole). There are sites suitable for the dissociation of an exciton. The formation of J-aggregates by dye molecules benefits color films from the viewpoints of sensitivity and color separation owing to the following facts. The saturated number of dye molecules per unit area of the grain surface is remarkably increased by the J-aggregate formation. Furthermore, the absorption band of J-aggregates of dye molecules is smaller in half-width, larger in peak intensity, and longer in wavelength than that of the monomers of the corresponding dye molecules. In addition, the J-aggregate formation enhances the migration and arrival of an exciton at a site suitable for its dissociation. However, excessive growth of Jaggregates decreases the concentration of sites suitable for the dissociation of excitons and enhances the migration of a dye positive hole for its recombination with an injected electron. It is therefore pointed out that the size of a J-aggregate should be optimized for the enhancement of the capture of a light image incident on a color film.View full abstractDownload PDF (2245K) -
I. Spectral Sensitization, Part 1. Progresses up to the 1920'sYasushi OISHI2007 Volume 70 Issue 5 Pages 295-305
Published: October 25, 2007
Released on J-STAGE: February 17, 2011
JOURNAL FREE ACCESSA historical review of the spectral sensitization of silver-halide materials with an emphasis on the innovation processes at the following main technological turning points: 1. inventing the dye sensitization, 2. focusing on the cyanines, 3. establishing the basic science of cyanines, and 4. creating the new synthesis.View full abstractDownload PDF (2234K) -
An Analysis by Ionic ConductivitySoc Man Ho KIMURA, Hideki KOMATSU, Tsuyoshi MITSUHASHI, Ken'ichi KUGE2007 Volume 70 Issue 5 Pages 306-311
Published: October 25, 2007
Released on J-STAGE: February 17, 2011
JOURNAL FREE ACCESSIn exploring the latent image formation mechanism of silver salt photothermographic materials, we measured the ionic conductivity of nanometer-scale silver halide crystal emulsions and observed the influence of silver carboxylate. We found that the ionic conductivity of nanometer-scale silver halide crystals, just as with micrometer-scale crystals, is in inverse proportion to crystal edge length. In addition, when silver carboxylate was mixed in a silver halide crystal emulsion, ionic conductivity decreased. Rather than silver atoms forming by means of interstitial silver ions of silver halide crystals, it may be that silver atoms are formed when silver ions from silver carboxylate react with trapped photoelectrons. These observations suggest both that silver carboxylate greatly affects the ionic process of latent image formation in silver salt photothermographic materials, and that the mechanism of latent image formation of silver salt photothermographic materials differs from that of conventional silver halide photographic materials.View full abstractDownload PDF (1052K)
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