Improved stabilities on surface-enhanced Raman scattering-active Ag/Al sub(2)O sub(3) films on substrates

As is shown in the literature, surface-enhanced Raman scattering (SERS)-active Ag films obtained by the salting-out of Ag colloids from solutions with some salts, are popularly used to examine the structure of analytes. SERS-active Ag nanoparticles (NPs) demonstrate more significant SERS effects than Au NPs, however, problems regarding the stabilities of SERS-active Ag NPs remain to be overcome. In this work, Ag/Al sub(2)O sub(3) colloids were prepared in 0.1 M HNO sub(3) solutions containing Al sub(2)O sub(3) NPs with higher heat capacity by sonoelectrochemical methods. SERS-active Ag/Al sub(2)O sub(3) films deposited on glass slides were prepared by the addition of a saturated NaCl solution in the prepared Ag/Al sub(2)O sub(3) colloids-containing solution. In an acceptable sacrifice of Raman intensity by ca.30% magnitude, the prepared Ag/Al sub(2)O sub(3) films markedly improved thermal stability by raising the operation temperature over 100 degree C, compared to Ag films. Meanwhile, aging of SERS enhancement capability in an atmosphere of relative humidity (RH) of 50% and 20% (v/v) O sub(2) at 30 degree C is significantly depressed using Ag/Al sub(2)O sub(3) films.