Fabrication And Application Of PDMS-Au MLF SERS Substrate In Mono-aromatic Hydrocarbons Detection

As an important technique in surface science, Surface enhanced Raman spectroscopy(SERS) can be used even for single molecule detecting. However, SERS detection of molecules without specific adsorption groups still remains a significant challenge. In this paper, an efficient method was developed to prepare a kind of composite substrates for SERS detection on mono-aromatic hydrocarbon. The main results are as follows:1. Fabricated the polydimethylsiloxane(PDMS) coated Au nanoparticles monolayer film composite substrate(PDMS-Au MLF) to improve the SERS detection ability on mono-aromatic hydrocarbons in water. By adjusting the concentration of PDMS, the composite substrate exhibited the maximum SERS intensity with a PDMS solution of 1.25%. The SERS performance of the as prepared PDMS-Au MLF composite substrate was examined by using benzene、toluene、nitrobenzene and xylene as probes. Finally, the results showed that for the detection of these mono-aromatic hydrocarbons, the composite substrate exhibited a 1-2 orders of magnitude higher SERS intensity compared with the naked Au MLF, which origined from the enrichment effect. Meanwhile, the detection limits differed from the kind of molecules.2.Finished the detection of mono-aromatic hydrocarbons in vapor-phase using composite substrates. The results showed that with a concentration of 20% PDMS base material, the as-prepared PDMS-Au MLF substrates reached the highest SERS capability for vapor detection. Compared with the naked Au MLF, PDMS-Au MLF showed a higher detection sensitivity with the mono-aromatic hydrocarbons in air.3.Developed an effective heavy metal ion detection technique based on the Au MLF substrate, which was modified with p-mercaptobenzoic acid(PMBA). With the sensibility between different kinds of heavy metal ions and the vibration spectrum peak of carboxylate radical, signle or mixtured heavy metal ion solution could be distinguished with different SERS intensity and frequency. Finally, the detection limit could as low as 10-8 mol/L.