2004 Fiscal Year Final Research Report Summary
Application of Pulse-Shaping and Multi-Pulse-Train for Control of Chemical Reaction in Condensed Phase and Surface
| Project/Area Number |
15350009
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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 |
Physical chemistry
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
WADA Akihide Tokyo Institute of Technology, Chemical Resources Laboratory, Associate Professor, 資源化学研究所, 助教授 (20202418)
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| Co-Investigator(Kenkyū-buntansha) |
KUBOTA Jun Tokyo Institute of Technology, Chemical Resources Laboratory, Research Associate, 資源化学研究所, 助手 (50272711)
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| Project Period (FY) |
2003 – 2004
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| Keywords | pulse train / optimal pulse shaping / adaptive control / control of excitation efficiency / control of reaction / coherent control / low-frequency vibration mode / pulse compression |
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| Research Abstract |
In order to examine the potentiality of multi pulse train and pulse shaping technique for control of chemical reaction, control of excitation process and excited states of perylene crystal was investigated by optimal pulse shaping technique. We succeeded in controlling the emission spectral feature of an α-perylene crystal ; the intensity of E-emission was increased by a factor of 1.4 without the change of Y-emission intensity. Furthermore, we found a near-infrared pulse shape whose multi-photon excitation efficiency is larger than that of a single femtosecond pulse by a factor of two. It was concluded from these results that pulse train and pulse shaping technique can control excitation process of molecules in condensed phase. In order to extend the application area of the pulse-shaping technique by increasing the pulse energy, the compression of femtosecond pulses obtained from a conventional regenerative amplifier was attempted by X^<(2)>:X^<(2)> process using BBO crystals. It was r
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ealized that the pulse width of 120 fs was narrowed to about 80 fs.
For the search of the molecular system which can be applied by the pulse shaping technique, the time-resolved experiments were carried out on several molecular-adsorbed-surface systems. It was found on isobutene adsorbed zeolite system that a short-lived species is produced by vibrational excitation of isobutene adsorbed OD groups. From the temporal behavior of OD band intensity, the desorption of isobutene takes places after the vibrational relaxation of OD mode finishes and before the system reaches thermal equilibrium. On the c(4×2)-CO/Ni(111) system, it was found that the site-hopping of CO molecule from hollow site to atop site was induced by the irradiation of intense near-infrared pulses. The hopping phenomenon was found to be entirely transient, with the surface returning to the pre-excited state within a few hundred picoseconds without desorption. The transient response of 10 molecular layers of D_2O ice on CO/Pt(111) at 130 K was also investigated under ultra-high vacuum following a near-infrared pump pulse by sum frequency generation (SFG) spectroscopy. It was revealed that the D_2O molecules in the ice crystalline layer formed an amorphous or liquid-like structure in response to the pumping without desorption of D_2O to the gas phase, and the crystals returned to the crystal structure on a sub-nanosecond time scale. Less
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