偶氮苯自组装“三明治”体系的增强拉曼光谱

Enhanced Raman Scattering From “Sandwiched” Azobenzene Self assembled Systems

偶氮苯自组装“三明治”体系的增强拉曼光谱于化忠张锦张浩力朱涛刘忠范（北京大学化学与分子工程学院智能材料研究中心北京１００８７１）ＥｎｈａｎｃｅｄＲａｍａｎＳｃａｔｅｒｉｎｇＦｒｏｍ“Ｓａｎｄｗｉｃｈｅｄ”ＡｚｏｂｅｎｚｅｎｅＳｅｌｆ┐ａｓｓｅｍｂｌ...

Abstract Silver island films were thermally deposited on the surface of azobenzene self assembled monolayers on gold, yields SERS active “Sandwiched systems” with a structure as Ag(island film)/Azo SAM/Au(substrate). Novel azobenzen alkanethiols, HS (CH 2) m NHC(O) Φ N=N Φ O C nH 2n+1 ,where m=2,3,4,6 for n=2, and m=2 for n=1,2,3,4, were used in the present study, which enable us to deliberately control the position of azobenzene functionality in such a ″sandwiched system″. The enhancement factor for SERS were measured as a function of the distance between Azo group and silver film (d 1), as well as the separation of Azo group from the gold surface(d 2). The measured SERS intensity decays approximately exponentially as a function of d 2, while there is a slightly increase initially then decreases with the increase of d 1. The result demonstrates that SERS highly relates to the underlying gold substrates as well as the upper silver island film, which is significant to the understanding of the SERS mechanism in this specialized configuration.