2001 Fiscal Year Final Research Report Summary
Nanometer scale real-time mapping of vibrations in pico second tempral region
| Project/Area Number |
12305007
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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 |
Applied physics, general
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| Research Institution | Hokkaido University |
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Principal Investigator |
MATSUDA Osamu Graduate School of Engineering, Hokkaido University, Associate Professor, 大学院・工学研究科, 助教授 (30239024)
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| Co-Investigator(Kenkyū-buntansha) |
INAGAKI Katsuhiko Graduate School of Engineering, Hokkaido University, Instructor, 大学院・工学研究科, 助手 (60301933)
MUTO Shunichi Graduate School of Engineering, Hokkaido University, Professor, 大学院・工学研究科, 教授 (00114900)
WRIGHT B. Oliver Graduate School of Engineering, Hokkaido University, Professor, 大学院・工学研究科, 教授 (90281790)
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| Project Period (FY) |
2000 – 2001
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| Keywords | atomic force microscopy / mode-locked laser / pump-probe measurement / heterodyne detection / nonlinear tip-sample interaction / local elasticity / cantilever dynamics / finite difference method |
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| Research Abstract |
In this research, we aim to develop a new microscope which has both nanometer spatial resolution and picosecond temporal resolution. It can be realized by the combination of the scanning probe microscope and the time-resolved measurement technique with ultrashort laser pulses. The former has the nanometer spatial resolution and the latter the picosecond temporal resolution. The combination of the ultra high speed optical switch with ultra short laser pulses and the scanning tunneling microscope has been already proposed along this way. It is proved, however, that the stray capacity between the sample and the microscope tip substantially reduces the spatial resolution when the tunnel current is switched very fast. As a way getting around the above problem, we propose a scanning probe microscope that detects ultrashort phonon pulses excited by ultrashort laser pulses.
The ultrashort light pulses from a mode-locked Ti-sapphire laser are divided into two optical paths. An optical delay line is used to introduce a time difference of ± 1 ns between the pulses in two paths. The pulses passing each line are modulated with different frequencies. A metal thin film sample is irradiated by the modulated light pulses to generate the ultrashort acoustic phonon pulses. The generated periodic surface displacement is detected by the atomic force microscopy. We considered this method theoretically and did actual experiments. In addition, we did related studies of the technique to estimate the local elasticity with nanometer spatial resolution by the ultrasonic force microscope and of the ultra high frequency phonon generation by a semiconductor quantum well structure.
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