2006 Fiscal Year Final Research Report Summary
Improvement of the Photoprocess Efficiencies by Colloidal Crystals Immobilized with Gel
| Project/Area Number |
16350124
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Polymer/Textile materials
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| Research Institution | Gifu University |
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Principal Investigator |
TSUCHIDA Akira Gifu University, Faculty of Engineering, Professor, 工学部, 教授 (60183076)
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| Co-Investigator(Kenkyū-buntansha) |
KIMURA Hiroshi Gifu University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (40313910)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Colloidal Crystal / Gel / Electro-Optic Effect / Reflection Spectra / Elastic Modulus of Crystal / Energy Transfer / Colloidal Silica / Surface Modification |
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| Research Abstract |
Colloidal crystals are the suspensions in which colloidal particles (50-300 nm in diameter) distribute regularly as they do in typical crystals like metals and protein crystals. The colloidal crystals are formed by the extended electrical double layers around the spheres and by the Brownian motion of the spheres. Colloidal crystals emit brilliant iridescent light by the Bragg reflection when they are illuminated by external light. On the other hand, light emission from the crystals inside is trapped partially within the crystal cage due to the Bragg reflection. This project attained the improvement of the photoprocess efficiencies by the photon trapping effect of colloidal crystals as follows. 1) Solid films which consist of colloidal particles with crystal structure were fabricated by drying the corresponding colloidal suspension. Reflection spectra and scanning probe microscope analyses proved that this drying dissipative structure provides very easy method in forming crystal arrange
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ment of colloidal spheres. It was found that Marangoni convection played an important roll for the pattern formation. 2) Colloidal crystals are immobilized by gelator in order to apply new functional materials. This colloidal crystals immobilized with gel also gave electro-optic responses. 3) The photon trapping efficiencies of colloidal crystals were quantitatively estimated by transmittance, reflection and fluorescence spectroscopy. The efficiency increased from about 40 to 60 % as the cell thickness increased from 1 to 10 mm. This result is attributed to an increase in the number of crystal layers perpendicular to the observation direction, i.e., heterogeneous crystal layers around the inner cell wall. 4) The efficiency of electronic excitation energy transfer from a photo-excited donor dye to an acceptor dye was studied in an exhaustively deionized colloidal silica suspension. The quantitative measurements showed that the enhancement of the transfer efficiency is 20 % or slightly more in the present experimental conditions. Less
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