卤酸根离子的近红外表面增强Raman散射

NEAR INFRARED SURFACE ENHANCED RAMAN SCATTERING OF HALATE IONS

用近红外激光激发研究了卤酸根离子在银胶中的表面增强Ｒａｍａｎ散射（ＳＥＲＳ）．实验结果表明，ＣｌＯ－３和ＢｒＯ－３离子在银胶颗粒表面只有单个的ＳＥＲＳ带，分别位于２２６和１５８ｃｍ－１处，而ＩＯ－３离子却在３３４和７５０ｃｍ－１处出现两个ＳＥＲＳ峰．这些结果表明ＣｌＯ－３和ＢｒＯ－３离子是通过氯和溴原子上的孤对电子吸附在银表面上，而ＩＯ－３离子则是通过其带负电的Ｏ－与银表面络合．这些卤酸根离子与银表面的作用强度依次为ＢｒＯ－３＞ＣｌＯ－３≈ＩＯ－３．它们引起吡啶的环呼吸振动的增强依次为ＣｌＯ－３＜ＩＯ－３＜ＢｒＯ－３．讨论了近红外ＳＥＲＳ的增强机制．

Surface enhanced Raman scattering (SERS) of halate ions in silver colloids is studied by near infrared (NIR) laser excitation.Ions of ClO - 3 and BrO - 3 in silver colloids give rise to SERS bands at about 226 and 158cm -1 ,respectively while IO - 3 ions on colloidal silver surface result in two Raman bands at about 750 and 334cm -1 .These results indicate that the interactions of ClO - 3 and BrO - 3 ions with silver surface are through their lone pair electrons of Cl and Br.Nevertherless,IO - 3 ions bond to silver surface through their negatively charged O -.The interaction strength of halate ions with silver are measured to be BrO - 3>ClO - 3≈IO - 3.The enhancements of the Raman modes of pyridine caused by addition of halate ions increase in the order ClO - 3<IO - 3<BrO - 3.The enhancement mechanisms in NIR SERS are discussed.