Structural evaluation of 6-(10-mercaptodecoxyl) quinoline self-assembled monolayer on gold by reflectance absorption infrared spectroscopy

Self-assembled monolayer (SAM) of 6-(10-mercaptodecaoxyl)quinoline (MDQ) on gold was characterized by reflectance absorption infrared spectroscopy (RA-IR). The molecular orientation of MDQ in the SAM was totally evaluated by comparing the RA-IR spectrum of the SAM with a transmission spectrum of a KBr pellet. It was found that the alkyl chain exhibit a tilting angle of 24±5° and a twisting angle of 50±5°. The results suggested that the quinoline moieties in the SAM form an order layer upon the hydrocarbon chain and do not disturb the packing of the alkyl chains obviously.