Ultrafast dynamics of carbon nanotube under alkylation studied by 10-fs visible pulse laser
Atsushi Yabushita1*, Yan-Qi Lin1, Kai-Yun Xie1, Nian-Zu She1, Daiki Uchida2, Yutaka Maeda2, Takayoshi Kobayashi1
1Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
2Department of Chemistry, Tokyo Gakugei University, Tokyo, Japan
* Presenter:Atsushi Yabushita, email:yabushita@mail.nctu.edu.tw
We have studied ultrafast dynamics of carbon nanotubes (CNTs) using ultrashort visible pulse laser with duration as short as 10fs. Relaxation lifetimes of electronic dynamics were estimated to be ~100 fs and ~ 1ps reflecting intraband and interband transition, respectively. When the CNT was alkylated, the intraband transition was faster than non-alkylated case. However, annealed alkylated sample was almost equal to that of non-alkylated sample within 2%. It shows that alkylation does not change the intraband transition rate but excess chemical modification has suppressed the intraband transition. Time-gated Fourier transform analysis has visualized time-dependent change of radial breathing mode of CNT reflecting the energy transfer between CNTs with different chiralities.

Keywords: ultrafast spectroscopy, carbon nanotube, vibrational dynamics, pump-probe measurement