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 thatTERS system in near-infrared (NIR) spectrum isreporting. The current study proposed a most favorableatomic force microscopy (AFM) tip based on anincorporated optimal grating structure close to the tipapex. The optimized M2 factor and the best spatialresolution are obtained as 5.9× 109 and 8.5 nmrespectively in the NIR range of radiation light. Theresults show that the optimized grating can effectivelyincrease the amount of intensity of electric field andimprove spatial resolution within the nanoslit between theAFM tip and substrate. The detection sensitivity ofmaterials can be done by our proposed AFM-TERSsystem. The difference between the maximumenhancement factors that are correlated to several undertest sample molecules show the selectivity potential ofthe proposed AFM-TERS system in material detectiontopic.