Sensitive Detection Of Aromatic Vapor Through PDMS-C₃H₇S-assisted SERS Amplification

Surface enhanced Raman spectroscopy（SERS） has emerged as a powerful analytical tool for identification of molecules by their fingerprint spectra. Due to its high sensitivity, SERS has been widely used in chemical sensing and environmental monitoring. However, the challenge of SERS detection for the molecules without specific groups（especially for aromatic vapors） still remains. In this work, we developed a novel PDMS-C₃H₇S-assisted SERS amplification approach for on-line SERS detection of aromatic vapor in the atmosphere with a high sensitivity and rapid response. The main results were listed as below:1. Fabricated Au@Ag nanoparticles monolayer film（Au@Ag MLF） at air/liquid interface. The roughness factor was estimated by the electrochemical oxygen adsorption, iodine adsorption and under potential deposition. The results revealed that the Au@Ag MLF exhibited the optimal SERS performance with the surface enhancement factor of 0.614 ×105 and the derivation in SERS intensity less than 1.45%. With increasing the layers of Au@Ag MLF, the enhancement effect was improved and the uniformity decreased remarkably. It demonstrated that the Au@Ag MLF could be developed as a promising SERS substrate with easy fabrication, high uniformity and activity.2. Developed a composite SERS substrate by integration of PDMS, C3H7 S and Au@Ag MLF（PDMS-C₃H₇S-Au@Ag MLF）. The device was designed and fabricated for the SERS detection of aromatic vapor in the atmosphere. By using benzene, toluene and three xylene isomers as probe, the adsorption to vapor and the SERS detection capability of the composite substrate was explored. It indicated that the SERS performance was critically depended on the thickness of PDMS, in which the PDMS with thickness of about 15-25 nm exhibited the strongest adsorption and high sensitivity of toluene vapor. It demonstrated that the composite surface layer brought the effective enrichment of target vapor for increasing the detection sensitivity. The cycle detection of this substrate was investigated. This strategy allows for rapid and sensitive SERS detection of weakly adsorbed vapor molecules at ambient condition.