A Study On Carbon Nanotubes Coated By Gold Nanoparticle As Surface-enhanced Raman Scattering Substrate

Since health and safety are the eternal pursuit of human, the detection aboutpoisonous and harmful substances is also increasing year by year. Terrorist bombingincidents occur all around the world frequently, and these lead to a serious threat tosafety of life and the stability of society. The single-molecule detection technique playsan important role in drugs and explosives detection; it attracts a lot of attention.Wavelength, intensity and polarization properties are all inherent characteristics.Spectrum method is considered as a powerful tool for detecting and studying elementstracing. Raman scattering is an effective analysis tool about material structures, but itssignal is weak. The cross-sectional of Raman scattering (10-30-10-25cm2) is smaller thanfluorescent scattering（~10-16cm2）,so the signal of Raman scattering is easy to drown inthe fluorescence signal. Compared to traditional Raman scattering, theSurface-enhanced Raman scattering (SERS) technology overcomes many disadvantages,such as low sensitivity, instability and destructiveness.This paper demonstrated a SERS substrate consisting of carbon nanotubes (CNTs)coated by gold-sol nanoparticles under the background of the development of Ramanscattering. The SERS enhancement from the three-dimensional (3D) CNT arrays, andtwo-dimensional (2D) CNT films substrates coated by different size Au nanoparticles,was experimentally verified with Rhodamine6G(R6G) as the probe analyte.FDTDmethod was developed for the SERS research, and then some experimental tests hadbeen carried out based on the computer simulation results, finally all of the sampleswere confirmed by spectrum analysis and we sum up the preliminary results.The workis as follows:①This SERS substrate included two kinds of samples because of CNTs’arrangement difference. Namely, one was Au/CNTs disordered film (two-dimensionalsamples), and the other was Au/CNTs ordered array (three-dimensional samples). Thispaper analyzed the factors affecting the distribution of electronic field by using FDTDsolution software.②CNTs and gold colloid were made by means of CVD and chemical methodrespectively.Then we assembled them together. The microstructure and the morphologyof the2D and3D samples were investigated by using scanning electron microscopy(SEM).The UV-VIS absorption spectrum of gold colloid had also been got. ③The Raman spectral measurement with R6G as SERS probe was carried out inthree aspects: different size of gold nano-particles, different arrangement of CNTs anddifferent concentration of probe molecule. The results showed that the3D CNTs arrayssubstrate had a higher Raman enhancement compared with2D CNTs films substrate andplanar glass substrate, due to the larger specific surface area of CNTs arrays and moregold nanoparticles adsorbed on the CNTs arrays sidewalls, which contributed theelectromagnetic field and Raman intensity.