Wb. Lacy et al., Quantitative SERS measurements on dielectric-overcoated silver-island films by solution deposition control of surface concentrations, ANALYT CHEM, 71(13), 1999, pp. 2564-2570
A simple method to control the dosing of small adsorbate molecules onto sol
id surfaces from liquid solution is applied to quantitative surface-enhance
d Raman scattering measurements on dielectric-overcoated silver-island film
s. The deposition method, based on substrate withdrawal from solution, is e
valuated by measuring fluorescence (ex situ) and optical absorption (in sit
u) of dye molecules deposited onto glass surfaces, Control of adsorbate sur
face concentrations was accomplished by varying the withdrawal rate and the
concentration of the dye in solution. The dosing method was used to study
the dependence of the electromagnetic contribution to SERS enhancement on s
urface coverage of scatterer. The sensitivity enhancement was found to be c
onstant for adsorbate coverages up to 60-80% of a monolayer. Beyond a full
monolayer, SERS enhancement for additional molecules deposited onto the sur
face was found to drop significantly, by as much as 1 order of magnitude.