Water Molecule Adsorption on Vertically Aligned Single-Walled Carbon Nanotubes

Abstract

A single walled carbon nanotube, which adsorbed water molecule in its nano channel, was observed using Raman spectroscopy, and two samples’ spectrums were compared under the same conditions. The SWNT samples that were vertically aligned on the silicon substrate were used. One of the samples was not covered by polymer whereas the other sample was covered by polymer. In our experiment, a nano channel was made using a nanosecond pulse laser (Nd:YAG laser). In order to adjust the focus, the sample was set on the automatic stage and controlled on the PC using a USB camera to watch closely. By moving the stage for over 30 seconds, the sample was processed to make the nano channel. The cell with the laser-processed sample in it was set on the Raman spectroscopy’s platform. Then, the cell was connected to the vacuum chamber and erlenmeyer flask by the valve. Both of the valves were opened first and left for a while to make the cell vacuum. Second, the vacuum chamber’s valve was closed and left for a while to let water molecule spread in the cell. Finally, the SWNT successfully adsorbed water molecule in its nano channel. Ar-ion laser was used in the Raman spectroscopy and the laser wavelength is 488nm. With the Raman spectroscopy, Radial Breathing Mode (RBM), D-band, and G-band were mainly observed. The RBM, D-band, and G-band originated from radial vibration frequency, defective structure, and graphite structure respectively. According to the sample types, the RBM spectrums were compared in our experiment.