1986 Fiscal Year Final Research Report Summary
Studies on the Surface Chemical Behaviors of Extremely Fine Particles by Multichannel Spectrophotometry
| Project/Area Number |
60550574
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
工業物理化学
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
TANAKA Toshio Technical College, Kyoto Institute of Technology, Professor, 大学併設短期大学部, 教授 (50026770)
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| Co-Investigator(Kenkyū-buntansha) |
IWASAKI Masashi Technical College, Kyoto Institute of Technology, Assistant, 工業短期大学部, 助手 (80135631)
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| Project Period (FY) |
1985 – 1986
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| Keywords | Multichannel Spectrophotometry / Ultrafine Particles / Silver Bromide / Catalysis / Cyanine Dyes / J-Aggregation / ストップトフロー法 |
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| Research Abstract |
Transient J-aggregation of 1,1'-diethyl-2,2'-cyanine chloride(Dye 1) from dilute aqueous solutions catalyzed by extremely fine silver bromide particles freshly prepared by rapid mixing of dilute silver-ion solutions with relatively concentrated bromide-ion solutions has been studied by stopped-flow multichannel spectrophotometry. Solutions of Dye 1 containing potassium bromide were mixed with silver perchlorate solutions in an Otsuka Electronics(formerly Union Giken) Type RA-416 stopped-flow rapid solution mixing device, and the time-resolved absorption spectra of the mixtures were recorded at intervals of 10 - 100 ms with an Otsuka Electronics Type MD-400 multichannel photodetector(equipped with a wide wavelength-range detector head). Even at low Dye 1 concentrations where normally no aggregation occurred, decay of the monomer absorption band of the dye began immediately after solution mixing, with concurrent growth of a transient J-band. The rate of this process was larger at lower temperatures and paralleled the rate of silver bromide nucleation, indicating that the latter was the rate-determining step of catalyzed J-aggregation. The reaction order of the J-aggregation was 2 - 3 when it was determined from the dependence on dye concentration of the growth rate of J-band, while it was a little larger than unity when determined from the decay rate of monomer band. This means that the catalyzed J-aggregation is not the sole cause for the monomer decay. At relatively high silver bromide concentrations, the monomer decay preceded the J-aggregation, the J-band in this case being broad and blue-shifted by about 10 nm. Thus, catalyzed J-aggregation is thought to compete with adsorption to silver bromide surface as monomers, the latter becoming predominant as the relative amount of silver bromide increases.
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