Substrate-induced Raman frequency variation for single-walled carbon nanotubes

Yingying Zhang; Jin Zhang; Hyungbin Son; Jing Kong; Zhongfan Liu

doi:10.1021/ja056793c

Substrate-induced Raman frequency variation for single-walled carbon nanotubes

J Am Chem Soc. 2005 Dec 14;127(49):17156-7. doi: 10.1021/ja056793c.

Authors

Yingying Zhang¹, Jin Zhang, Hyungbin Son, Jing Kong, Zhongfan Liu

Affiliation

¹ Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.

PMID: 16332042
DOI: 10.1021/ja056793c

Abstract

We report on the monotonic Raman frequency shift and intensity variation when a laser spot moves along the same single-walled carbon nanotube (SWNT) for both the radial-breathing mode (RBM) and the G-band. Our substrates are Si wafers coated with thermal oxide, and trenches with widths of 1-80 mum are etched in the SiO2 by photolithography and reactive ion etching. SWNTs are grown by chemical vapor deposition and lie on top of the SiO2 and across the trenches. When the laser spot moves from the middle of the trench to the SiO2 region along the nanotube, we observe a clear upshift in the RBM and G-band frequencies and a decrease of intensity. The effect is more significant with large ( approximately 2 nm) diameter nanotubes and appears to be chirality dependent. These studies provide important information about environmental effects on single-walled carbon nanotube resonant Raman spectroscopy.