Evanescent-field-induced Raman scattering for bio-friendly fingerprinting at sub-cellular dimension

Molecular and plasmonic resonances on tip-enhanced Raman spectroscopy

Plasmon has been widely investigated and applied, because it can greatly enhance molecular Raman spectral intensity. In this study, the resonance Raman effect of the tetra-tert-butylnaphthalocyanine (TTBN) is analyzed, including the Raman wave number shift and enhancement factor, resulting from light of different incident wavelengths. Furthermore, the optical properties of TTBN are obtained, such as charge transfer, the electronic circular dichroism (ECD) spectrum, etc. Lastly, we study the tip-enhanced Raman spectroscopy (TERS) by adjusting the parameters of the metal tip to achieve the highest electromagnetic enhancement at different incident wavelengths. Combining the resonance excitation effect and the tip enhanced Raman effect, the enhancement factor of TERS can reach up to 10⁸-10⁹. This study provides significant help for a profound understanding of the TERS mechanism.