【摘要】 利用激光刻蚀法制备了具有"化学纯净"表面的银岛膜,该岛膜有很好的表面增强特性。利用表面增强拉曼光谱和表面增强红外光谱对胸腺嘧啶分子在银岛膜表面的吸附状态进行了对比研究。表面增强拉曼光谱中CN和C—O伸缩振动模式的出现表明胸腺嘧啶分子由原来的酮式结构变成了烯醇式结构;C(4)O伸缩振动谱带明显增强和N(3)的去质子化异构体特征峰的存在证明胸腺嘧啶分子是通过O(8)和N(3)的共同作用倾斜地吸附在银岛膜表面。对10-5 mol.L-1胸腺嘧啶在银岛膜表面上的红外光谱利用欧米采样器进行了反射法测量,发现其红外吸收增强了200倍。红外信号分析的结果支持了胸腺嘧啶分子通过O(8)与银表面发生相互作用的论断,同时也可得出胸腺嘧啶倾斜地吸附在银岛膜表面的结论。更多还原

【Abstract】 Thymine,being one of the four nucleobases in the nucleic acid of DNA,has received an increasing interest due to itspotential importance in genetics and possible applications in medical science.In the present study,adsorption of thymine onlaser-ablated silver island films was comparatively analyzed by means of surface-enhanced Raman scattering(SERS)and surface-enhanced infrared absorption(SEIRA).Two new bands at 1 305and 1 573cm-1 appeared in the SERS spectrum of thymine onsilver island films and represented that the molecule configuration of thymine hydrolyzed ion compound changed its structurefrom a keto form to an enol one.The greater enhancements of in-plane ring breath vibration bands and of 1 649cm-1 band asso-ciated with C(4)O stretching vibration clearly suggested that the thymine molecules were adsorbed on the silver surface viaO(8).The interaction of N(3)with silver surface could be inferred by the emergence of a stronger peak at 773cm-1,which wasassigned to the ring breath caused by the stretching vibration of the C(6)—N(3)—C(2).The blue shift of ring breath vibrationfrom 749to 773cm-1 indicated that thymine ring should have some weak interaction with silver surface,i.e.,there was a cer-tain angle between the thymine ring and the silver surface.To sum up,the SERS spectrum indicated that thymine adsorbed onthe silver surface as enolate through the O(8)and N(3)atoms.The molecular plane assumed a tilted orientation with respect tothe silver surface.Laser-ablated silver island films also exhibited a good surface enhancement to infrared absorption for thymine.Enhancement factor was estimated to be about 200under our experimental condition.There was no shift of C(2)O stretc-hing vibration in SEIRA spectrum,revealing that O(7)was not involved in the adsorption process.Consistent with our SERSspectrum,the greater enhancement of the thymine ring deformation vibration(1 730cm-1)in SEIRA agreed a tilted orientationof thymine on silver surface.更多还原