1999 Fiscal Year Final Research Report Summary
Molecular association in solution controlled by photon pressure of a focused laser beam
| Project/Area Number |
09304067
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
機能・物性・材料
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| Research Institution | Osaka University |
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Principal Investigator |
MASUHARA Hiroshi Department of Applied Physics, Osaka University, Professor, 大学院・工学研究科, 教授 (60029551)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Keiji Research Institute for Electronic Science, Hokkaido University, Professor, 電子科学研究所, 教授 (00183822)
ASAHI Tuyoshi Department of Applied Physics, Osaka University, Associate Professor, 大学院・工学研究科, 助教授 (20243165)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Photon presuure / Colloid particles / Focused laser beam / A single microparticle / Laser manipulation / Micro Browniam motion / Microscope / Polarizability |
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| Research Abstract |
We have studied a new phenomenon induced by photon pressure due to a focused near infrared laser beam; a single μm-sized particle is formed by trapping nm colloid particles such as polymer, ultramicroparticle, and micelles. This laser manipulation can be extended to form molecular assembly structure under a novel perturbation of photon pressure. By investigating various colloid particles with laser trapping-spectroscopy methods, the following interesting results have been obtained. Photon pressure of a focused beam overcomes electrostatical repulsion between charged polymer micelles. The minimum size of colloid which can be trapped by the focused laser beam is determined to be 12 nm, while molecular polarizability was demonstrated to be a responsible parameter. Chemical and optical mechanism can explain well gathering of nm colloid particles and the following formation of a μm-sized particle. The formed microparticle has a shape like a rugby ball, around which temperature gradient is produced by efficient photothermal conversion in water molecules. The trapped microparticles disappear when the focused laser beam is switched off, so that we have proposed a new method to fix it on polymer substrate by nanosecond UV-laser induced transient melting.
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