Abstract:

A novel method of modifying the probe of SERS-optical sensor is described. By using laser-induced deposition and growth of Ag nanoparticles,we prepared a new type of Ag-deposited film with the appearance of annual rings on the fiber tip. A 6 cm-long silica fiber is immersed in the mixture of AgNO₃ and citrate. A 514.5 nm laser with the power of 4.2 mW is used to reduce the Ag(Ⅰ) to Ag(0) and induced Ag(0) to deposit onto the fiber tip. SERS spectra of a probe molecule(BPENB) are used to monitor the deposition process. The optical and AFM images display the macro- and micro-appearance of Ag-deposited film. These results show that the laser-induced deposition is a simple and rapid method for modifying the probe of SERS-optical sensor. The Ag film with the proper thickness and roughness is prepared within only about 4.5 min. Moreover,the Ag deposition film prepared by this method shows not only easy reproduction but also remarkable SERS activity. The mechanism of the laser-induced Ag deposition onto the fiber tip was also discussed.

Key words: Laser induction; Ag deposition; SERS; Optic fiber probe