ИСТИНА

Surface Enhanced Raman Scattering (SERS) spectroscopy has proven to be a powerful diagnostic tool due to both its ultrasensitivity (as it provides label-free detection of molecules at very low concentrations) and specificity (as it allows identifying molecules by their vibrational fingerprint). The greatest enhancement is achieved while resonance Raman effect takes place – a plasmonic band position of nanoparticles, a laser excitation wavelength and an absorption range of analyzing molecules coincide. However, such important analytes as polycyclic aromatic hydrocarbon (PAH) and sulfur heterocyclic (PASH) compounds existing in raw oil or as technogenic pollutants absorb in the UV-region, far to the plasmonic band of for silver (ca. 400 nm) or for gold (ca. 500 nm) nanoparticles, therefore these molecules could become practically ‘‘invisible’’ for SERS. This report suggests a novel approach encompassing silver surface modification succeed in getting highly repeatable SERS-signal for PASH such as dibenzothiophene (DBT) and its derivatives (e.g. 4,6-dimethyldibenzothiophene, DMDBT) and PAHs such as 1-methylnaphtalene, acenaphthene, and fluoranthene which were ‘visualized’ by trapping into colored charge transfer complexes (CTCs) with the appropriate π-acceptors, e.g. 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or 7,7,8,8-tetraquinodimethane (TCNQ) for various PAHs as π-donors.