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1. 浙江工业大学 化学工程学院, 绿色化学合成技术国家重点实验室培育基地,浙江 杭州,310032
2. 浙江省家具与五金研究所,浙江 杭州,310007
纸质出版日期:2015-12-10,
收稿日期:2015-8-30,
修回日期:2015-9-25,
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刘江美, 刘文涵, 滕渊洁等. 2-噻吩甲酸在Fe<sub>3</sub>O<sub>4</sub>@Ag基底上的吸附及表面增强拉曼光谱[J]. 发光学报, 2015,36(12): 1477-1484
LIU Jiang-mei, LIU Wen-han, TENG Yuan-jie etc. Adsorption Behavior of 2-Thiophene Carboxylic Acid on Fe<sub>3</sub>O<sub>4</sub>@Ag Substrate Investigated by Surface-enhanced Raman Scattering[J]. Chinese Journal of Luminescence, 2015,36(12): 1477-1484
刘江美, 刘文涵, 滕渊洁等. 2-噻吩甲酸在Fe<sub>3</sub>O<sub>4</sub>@Ag基底上的吸附及表面增强拉曼光谱[J]. 发光学报, 2015,36(12): 1477-1484 DOI: 10.3788/fgxb20153612.1477.
LIU Jiang-mei, LIU Wen-han, TENG Yuan-jie etc. Adsorption Behavior of 2-Thiophene Carboxylic Acid on Fe<sub>3</sub>O<sub>4</sub>@Ag Substrate Investigated by Surface-enhanced Raman Scattering[J]. Chinese Journal of Luminescence, 2015,36(12): 1477-1484 DOI: 10.3788/fgxb20153612.1477.
采用共沉淀法合成Fe
3
O
4
纳米颗粒
再以柠檬酸三钠还原AgNO
3
获得了具有SERS活性的Fe
3
O
4
@Ag磁性纳米复合材料。基于密度泛函理论(DFT)的量子化学计算方法和表面增强拉曼光谱(SERS)技术
从理论计算和实验测定表征探讨了2-噻吩甲酸(2-TCA)在Fe
3
O
4
@Ag表面的吸附行为和增强效应。结果表明:理论计算得到的拉曼光谱与实际测得的常规拉曼光谱基本一致
而在DFT理论计算中所键连的Ag原子数越多
与实测值就越接近。溶液的浓度和pH对拉曼增强效果有很大的影响
当溶液的pH=3且浓度为110
-4
molL
-1
时有最大拉曼增强效应。峰强随2-TCA浓度的增加呈现先增大后减小的趋势
浓度过大会导致大量2-TCA分子吸附聚集在Ag表面形成局部"拥堵"
阻碍了激发光尤其是光谱信号的散射通过
从而减弱了拉曼增强效应。pH的变化使溶液中2-TCA分子形态发生改变
结构形态不同
其在Ag表面的吸附方式也不同。中性C
4
H
3
SCOOH分子以环上S:形式垂直吸附键合在Ag表面
形成SAg配位键而产生SERS光谱。-1价C
4
H
3
SCOO
-
离子以SAg配位和OAg共价"双键合"侧卧方式共同吸附在Ag表面而产生SERS光谱。在Ag表面
以单独SAg配位键吸附或键合的能力比SAg配位和OAg共价共同吸附方式要弱
但其产生的SERS信号更强
故2-TCA中性分子比2-TCA
-
离子更有利于SERS的产生。随着pH值的增加
溶液中的2-TCA由中性分子逐渐转化为-1价的C
4
H
3
SCOO
-
离子
因而在pH
>
3以后
拉曼增强效应逐步减弱。
Fe
3
O
4
magnetic nanoparticles were firstly synthesized by co-precipitation method
and Fe
3
O
4
@Ag magnetic material which has improved SERS effect was further prepared by reduction of AgNO
3
using sodium citrate. Both density functional theory (DFT) and surface-enhanced Raman scattering (SERS) spectroscopy technique were used to investigate the adsorption behavior and enhancement effect of 2-thiophene carboxylic acid (2-TCA) on the Fe
3
O
4
@Ag surface. The results show that Raman spectra of the theoretical calculation and the determination are basically identical
and the more Ag atoms are introduced in theoretical calculation
the closer the measured value is to the theoretical value. The concentration and pH of the solution have great influence on the Raman enhancement effect
and the solution of 110
-4
molL
-1
at pH=3 can present excellent Raman signal response. The SERS effect increases initially and decreases afterwards with the increasing of concentration
which can be inferred that a lot of 2-TCA molecules are adsorbed and gathered on the Ag surface to form a local "congestion" and interfere the transmission of the excitation light
especially spectroscopic signal scattering. 2-TCA molecule morphology is changed with the increasing of pH
and the adsorption mode is influenced by the molecule morphology. The neutral C
4
H
3
SCOOH is vertically adsorbed on the Ag surface by the formation of SAg coordination bond. However
C
4
H
3
SCOO
-
anion is adsorbed on Ag surface with SAg coordinate bond and OAg covalent bond which is named as "double-bonged" side pattern. Although the adsorption of SAg coordinate bond is weaker than "double-bonged" side pattern
the SERS signal is stronger
because the neutral 2-TCA molecules are more beneficial to the generation of SERS signal comparing with 2-TCA
-
anion. The neutral 2-TCA molecules are gradually transformed into C
4
H
3
SCOO
-
anion with the increasing of pH
which leads to the decreasing of SERS effect gradually after pH
>
3.
2-噻吩甲酸表面增强拉曼光谱Fe3O4@AgDFT化学吸附
2-thiophene carboxylic acidSERSFe3O4@AgDFTchemical adsorption
Chandra S, Chowdhury J, Ghosh M, et al. Exploring the pH dependent SERS spectra of 2-mercaptoimidazole moleculeadsorbed on silver nanocolloids in the light of Albrecht's "A" term and Herzberg-Teller charge transfer contribution [J]. J. Colloid Interf. Sci., 2013, 399:33-45.
Zhu Y H, Shen J H, Zhou K F, et al. Multifunctional magnetic composite microspheres with in situ growth Au nanoparticles: A highly efficient catalyst system [J]. J. Phys. Chem. C, 2011, 115:1614-1619.
Vanesa L P, Sara A C, Paula C A, et al. Plasmonic mesoporous composites as molecular sieves for SERS detection [J]. J. Phys. Chem. Lett., 2013, 4:2715-2720.
Chen L, Yang X G, Zheng X M, et al. Surface-enhanced Raman scattering of thiabendazole adsorbed on silver nanoparticles [J]. Spectrosc. Spect. Anal.(光谱学与光谱分析), 2013, 33(12):3244-3248 (in Chinese).
Byunghee H, Namhyun C, Ki H K, et al. Application of silver coated magnetic microspheres to SERS-based optofluidic sensor [J]. J. Phys. Chem. C, 2011, 115:6290-6296.
Zhai Y M, Zhai J F, Wang Y L, et al. Fabrication of iron oxide core/gold shell submicrometer spheres with nanoscale surface roughness for efficient surface-enhanced Raman scattering [J]. J. Phys. Chem. C, 2009, 113:7009-7014.
Li Q X, Beatrice S, Rong W, et al. Catecholamine-induced electroless metallization of silver on silica@polymer hybrid nanospheres and their catalytic applications [J]. Ind. Eng. Chem. Res., 2014, 53:3116-3124.
Liu W H, Yuan R H, Teng Y J, et al. Chemical adsorption of thiosalicylic acid on silver surface investigated by surface-enhanced Raman scattering [J]. Spectrosc. Spect. Anal.(光谱学与光谱分析), 2013, 33(9):2433-2437 (in Chinese).
Zhang S S, Wen Y H, Ding C F, et al. Dean's Handbook of Organic Chemistry [M]. Beijing: Chemistry Industry Press, 2006:698 (in Chinese).
Subhendu C, Joydeep C, Manash G, et al. Adsorption of 3-thiophene carboxylic acid on silver nanocolloids: FTIR, Raman and SERS study aided by density functional theory [J]. J. Phys. Chem. C, 2011, 115:14309-14324.
Cecilia I V, Gustavo F S A, Marcia L A T, et al. Monitoring of silver electrode position onto HOPG electrodes in the presence of picolinic acid by in situ surface-enhanced Raman spectra measurements [J]. J. Phys. Chem. C, 2014, 118:4167-4180.
Liu W H, Ma S Z, Teng Y J, et al. Self-assembly behavior of 2-mercaptobenzimidazole on silver electrode investigated by surface enhancement raman scattering [J]. Chin. J. Lumin.(发光学报), 2015, 36(1):106-112 (in Chinese).
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