Abstract：In this paper, the preparation of an optical fiber surface-enhanced Raman scattering (SERS) probe by laser-induced deposition was studied, and the SERS performance of the probe was tested. The effect of the concentration of gold nanorod solution on the sensitivity of the optical fiber probe was discussed. The results show that two kinds of nanostructures——gold nanorod clusters and gold nanorod dispersion can be formed on the optical fiber facet by laser induction of gold nanorods with different concentrations. The induced deposition pattern is affected by the factors such as the concentration of gold nanorod solution, laser power and induction time. Induced by a laser with a power of 5 mw, SERS probes with different patterns were prepared in 1.5×10-9, 1.0×10-9 and 7.5×10-10 mol·L-1 gold nanorods solution after 5 min deposition. Synthesized by the crystal seed method, the morphology of gold nanorods was observed by transmission electron microscope (TEM). Moreover, the length-to-diameter ratio of the synthesized gold nanorods was about 3.8 according to TEM image analysis. The morphology of gold nanorods and fiber-modified ends after laser-induced deposition was observed with a scanning electron microscope (SEM). The distribution of gold nanorods on the fiber end surface was relatively dispersed in 7.5×10-10 mol·L-1 gold nanorod solution by laser induction, while induced by laser in 1.5×10-9 and 1.0×10-9 mol·L-1 gold nanorods solution, a large number of gold nanorods clustered at the end of the optical fiber. It is taking 4-Aminothiophenol (4-ATP) as the sample molecule, and the SERS performance of the optical fiber probe was detected by Raman spectrometer. In order to facilitate comparison, the Raman intensity at the Raman shift of 1 079.972 cm-1 was selected for mapping. The results showed that the laser-induced fiber probe performs better at a gold nanorod concentration of 7.5×10-10 mol·L-1. The pattern’s hot spot distribution was simulated by the FDTD (finite-difference time-domain) method, which further explained the better performance of the laser induced fiber probe prepared at the concentration of 7.5×10-10 mol·L-1 gold nanorods. To test the repeatability of the fiber probe, after the SERS spectrum was tested, the fiber was immersed in anhydrous ethanol for 24 hours to make 4-ATP fully dissolved in alcohol. 15 days later, the SERS detection performance of optical fiber probes was detected again, and the same spectrogram was obtained as that detected before, which proved that the obtained optical fiber SERS probes had strong reusability. The laser-induced preparation of fiber probes can realize the repeated and batch preparation of SERS probes with high sensitivity with simple operation, low cost, short preparation time and so on.
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