ИСТИНА

Surface Enhanced Raman Scattering (SERS) spectroscopy has proven to be a powerful diagnostic tool due to both its ultrasensitivity (as it can provide label-free detection of molecules at extremely 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 sulfur heterocyclic (PASH) and hydrocarbon (PAH) compounds, e.g. dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (DMDBT), 1-methylnaphtalene, acenaphthene, fluoranthene, etc. In order to meet new environmental regulations of 0.1 mmol l-1 it is necessary selectively and precisely quantitatively detect PAHs and PASHs in their complex mixtures in various oil and environment samples. Unfortunately, these compounds existing in raw oil as impurities and in environment 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 PASHs and PAHs which were ‘visualized’ as effective π-donors by trapping them 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).