Design of NIR-TERS System Based on Optimized Grating on the AFM Probe Under Radial Polarized Light for Detection of Molecular Sample

To the best of our knowledge, it is for the first time that TERS system in near-infrared (NIR) spectrum is reporting. The current study proposed a most favorable atomic force microscopy (AFM) tip based on an incorporated optimal grating structure close to the tip apex. The optimized M2 factor and the best spatial resolution are obtained as 5.9× 109 and 8.5 nm respectively in the NIR range of radiation light. The results show that the optimized grating can effectively increase the amount of intensity of electric field and improve spatial resolution within the nanoslit between the AFM tip and substrate. The detection sensitivity of materials can be done by our proposed AFM-TERS system. The difference between the maximum enhancement factors that are correlated to several under test sample molecules show the selectivity potential of the proposed AFM-TERS system in material detection topic.