| 研究実績の概要 |
In this fiscal year, two main activities for thee project were successfully performed: (1) improvement of the THz emission intensity and (2) establishment of the optical pump-THz probe measurement system for investigation of ultrafast dynamics. (1) Was achieved by upgrading the power supply of the photoconductive antenna from a DC to an AC power source. By doing this, the THz emission intensity was improved by about five times. Consequently, this has led to the improved signal to noise ratio which was one of the main problems encountered in the previous fiscal year. Before coupling the THz light to the SPM tip, I established a far field optical pump, THz-probe setup. For this experiment, the THz pulse from the PCA is used as a probe while a second pump near infrared pump pulse was used as the optical pump. For this experiment, it is important to achieve the most intense pump pulse possible. To achieve this the original beam splitter of the THz-TDS setup was changed from 50:50 to 90:10 and a second 90:10 beam splitter was introduced. Also a secondary mechanical delay line was introduced. I carefully designed the whole experimental setup to allow us to perform three experiments by simply changing some mirrors. Moreover, the graphene sample on Au(111) surface was successfully investigated using STM-TERS in this fiscal year.
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