title: Tip-enhanced Raman spectroscopy with silver-coated optical fiber probe in reflection mode for investigating multiwall carbon nanotubes.
abstract: We developed a tip-enhanced Raman spectrometer (TERS) with reflection mode. The instrument, with a scanning shear-force microscope (ShFM) and a side-illumination Raman spectroscope, can overcome the diffraction limit and has high sensitivity. A chemical method to fabricate optical fiber probes with Ag coating is proposed. The local electromagnetic responses of the silver-coated optical fiber probe are numerically analyzed by the finite-difference time-domain method, and the excitation wavelength is optimized to resonate with the localized surface plasmons (LSP) of the probe tip. The instrument is applied to investigate a single multiwall carbon nanotube. The experiment results indicate that our TERS instrument has a spatial resolution better than 70 nm, and the enhancement factor is about 5 x 10(3).
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 10084, China. wangrui05@mails.tsinghua.edu.cn
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Fenghuan
authors.initials: F
authors.lastname: Hao
authors.forename: Mingqian
authors.initials: M
authors.lastname: Zhang
authors.forename: Qian
authors.initials: Q
authors.lastname: Tian