| Project/Area Number |
16072212
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
|
| Allocation Type | Single-year Grants |
|---|
| Review Section |
Science and Engineering
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
MIYASAKA Hiroshi Osaka University, Graduate School of Engineering Science, Professor (40182000)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
ITO Syoji Osaka University, Graduate School of Engineering Science, Assistant Professor (10372632)
|
|---|
| Project Period (FY) |
2004 – 2006
|
| Project Status |
Completed (Fiscal Year 2006)
|
| Budget Amount *help |
¥27,500,000 (Direct Cost: ¥27,500,000)
Fiscal Year 2006: ¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 2005: ¥11,200,000 (Direct Cost: ¥11,200,000)
Fiscal Year 2004: ¥9,000,000 (Direct Cost: ¥9,000,000)
|
|---|
| Keywords | Molecular crystal / Photo-switching / Single molecule detection / Mesoscopic systems / レーザー誘起結晶化 / 相分離 / レーザー多光子顕微鏡 / 単一分子計測 / 結晶成長 / レーザー誘起現象 / フェムト秒分光 / ナノ秒分光 / 結晶核生成 / レーザー分光 |
|---|
| Research Abstract |
With a view to elucidating molecular dynamics in the nucleation process of organic crystals in solids, we have studied model systems, pyrene molecules in low temperature glassy matrices of mixture solvent consisting of isopentane and methylcyclohexane. In the series of experiments we demonstrated that irradiating several thousands of nanosecond laser pulses at 355 nm to the model system induced the efficient aggregation of the solute in the solid matrices even at 77 K. During the crystallization induced by successive UV irradiation, an emission peak that could be attributed to the excimer of pyrene increased in intensity with an increase in the shot-number of the UV pulse, while the excimer emission was not detected without laser irradiation. The excimer emission appeared even by single shot irradition of the UV pulse, which indicates that the single shot of the laser pulse enabled pyrene molecules to stick together by translational/rotational diffusion. This can be explained by transient melting of the glassy matrices induced by the laser irradiation. Time-resolved fluorescence measurements from ps to ns region revealed that the solute molecules moved and formed excimer within the time-width of the UV pulse; the excimers were frozen before dissociation because of short duration of the transient melting almost same as that of the UV pulse and longer lifetime of pyrene excimer (〜 100 ns order). This different time-scale between aggregation and dissociation can explain the efficient aggregation of the solute by UV irradiation in this system.
|
