Abstract

Surface enhanced Raman spectroscopy (SERS) is a well-known surface-sensitive spectroscopic technique for enhancing Raman signal of molecules adsorbed on rough conducting surfaces. In present study a possible application of excimer laser irradiation in SERS substrate preparation is demonstrated. A polyimide foil on a rotating target holder was irradiated by 240 ArF excimer laser (λ=193 nm, FWHM=20 ns) pulses with an average fluence of 40 mJ/cm². Due to the continuous rotation concentric homogeneous zones having specific nanostructures evolved on the laser treated surface. After the laser processing, the sample was coated with 40 nm thick silver layer by PLD to create a conducting layer for SERS. The SERS activity of the different annular parts of the irradiated spot was investigated by a Raman Microscope at 780 nm wavelength. 10⁻³ mol/dm³ aqueous solution of Rhodamin 6G (R6G) was used as reference sample. It was found that the intensity of the characteristic peaks of the R6G spectra depended significantly on the surface morphology of the tested area, however inside the annular regions homogeneous terrains were found. Figure 1 shows the Raman spectrum of the R6G dye solution on the best laser treated area covered by a 40 nm thick silver film, supplemented with a reference spectrum: R6G on untreated polyimide surface also covered by a silver film. It can be clearly seen that the Raman spectrum measured above the laser treated surface is much more intense than in the case of the untreated area, while both of them are coated by silver layers of the same thickness.

© 2013 IEEE