波长检测型表面等离子体共振传感器对硫堇电聚合成膜的原位分析

利用波长检测型表面等离子体共振(SPR)传感器对硫堇在金膜表面的电化学聚合成膜过程进行了跟踪分析.结果表明,在固定入射角下SPR共振波长随循环伏安扫描周数的增加而线性红移,表明聚硫堇膜的生长是匀速的;扫描100周后共振波长红移总量为96.6 nm.对该实验结果进行理论拟合,得出聚硫堇膜的厚度约为71 nm.聚硫堇膜在酸性缓冲液中的电化学活性很高,其电化学反应过程受扩散控制,在一个完整的循环伏安扫描过程中SPR共振波长的变化完全可逆,说明聚硫堇膜的氧化反应和还原反应是一对可逆过程.与还原态聚硫堇膜相比,氧化态聚硫堇膜对应的SPR共振波长较大,说明氧化态聚硫堇膜折射率高.

Studies of Electrochemical Polymerization of Thionine Using a Wavelength-interrogated Surface Plasmon Resonance Sensor

The electrochemical polymerization of thionine on gold layer was investigated by using a wavelength-interrogated surface plasmon resonance(SPR) sensor that operates at a fixed angle of incidence.The experimental results show that the resonant wavelength of SPR sensor linearly increases with increasing the number of voltammetry scanning cycles and the total redshift of resonance wavelength is 96.6 nm after 100 scanning cycles.The findings indicate that the film growth rate in every scanning cycle is constant and the poly(thionine) film formed after 100 cycles is ca.71 nm thick based on the best fit of simulation results to the measured data.The poly(thionine) film in acidic buffer solution exhibits high electrochemical activity and its electrochemical reaction is diffusion-controlled.The resonant wavelength of SPR sensor reversibly changes in a voltammetry scanning cycle, indicating the complete reversibility of electrochemical oxidation-reduction reactions for the poly(thionine) film.Compared with the reduced poly(thionine) film, the oxidization of poly(thionine) film leads to a redshift of resonant wavelength, giving a sign that the refractive index of oxidized poly(thionine) film is higher than that of the reduced one.