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1、金纳米颗粒在不同包裹介质中的超快等离子体动力学（英文） 陈晓宇 王经东 于安池 中国人民大学化学系 摘 要： 为了探究不同包裹介质对金纳米颗粒的超快等离子体动力学的影响, 本文我们制备了聚苯乙烯磺酸钠 (PSS) 、二氧化硅 (SiO 2) 、二氧化钛 (TiO 2) 以及氧化亚铜 (Cu 2O) 四种介质包裹的金纳米颗粒。运用飞秒泵浦探测技术, 我们分别获得了 PSS、SiO 2、TiO 2以及 Cu2O 包裹的金纳米颗粒在不同时间延迟下的飞秒瞬态吸收光谱。我们发现 TiO2包裹的金纳米颗粒的飞秒瞬态吸收光谱特征与PSS 和 SiO2包裹的金纳米颗粒的飞秒瞬态吸收光谱特征有很大的不同, 但与
2、Cu2O 包裹的金纳米颗粒的飞秒瞬态吸收光谱特征相似。全面分析PSS、SiO 2、TiO 2和 Cu2O 包裹的金纳米颗粒的超快等离子体动力学行为, 我们发现在 TiO2和 Cu2O 包裹的金纳米颗粒体系中光激发金纳米颗粒的等离子体共振吸收后产生的激发电子可以有效地转移到 TiO2和 Cu2O 的导带上。关键词： 飞秒瞬态吸收光谱; 等离子体共振激发; 电子转移; 金纳米颗粒; 核/壳结构; 作者简介：YU An-Chi, Email: ;Tel: +86-10-6251-4601.收稿日期：April 26, 2017基金：supported by the National Natural
3、Science Foundation of China (21373269) Effect of Surrounding Media on Ultrafast Plasmon Dynamics of Gold NanoparticlesCHEN Xiao-Yu WANG Jing-Dong YU An-Chi Department of Chemistry, Renmin University of China; Abstract： Herein, we prepared four samples, namely gold/poly (sodium-p-styrenesulfonate) (A
4、u/PSS) , gold/silicon dioxide (Au/SiO2) , gold/titanium dioxide (Au/TiO2) , and gold/cuprous oxide (Au/Cu2O) core/shell nanocomposites, to investigate how the surrounding medium affects the ultrafast plasmon dynamics of Au nanoparticles (NPs) . We recorded femtosecond transient absorption spectra of
5、 Au NPs in Au/PSS, Au/SiO2, Au/TiO2, and Au/Cu2O core/shell nanocomposites at various time delays. We found that the spectral featuresin the femtosecond transient absorption spectra of Au NPs in Au/TiO2 and Au/Cu2O core/shell nanocomposites were dramatically different from those of Au NPs in Au/PSS
6、and Au/SiO2 core/shell nanocomposites. A comprehensive analysis of the ultrafast plasmon dynamics of Au NPs in the core/shell nanocomposites revealed that following excitation of the resonance plasmon band of Au NPs, the exited electrons could be efficiently transferred into the conduction bands of
7、TiO2 and Cu2O in Au/TiO2 and Au/Cu2O core/shell nanocomposites.Keyword： Femtosecond transient absorption spectroscopy; Plasmon resonance excitation; Electron transfer; Gold nanoparticle; Core/shell structure; Received： April 26, 20171 IntroductionGold nanoparticles (Au NPs) have been extensively inv
8、estigated due to their potential applications in sensing, photovoltaics, catalysis, imaging, and photothermal therapy.Many of these applications are attributed to their unique optical properties.The main optical signature of Au NPs is its localized surface plasmon resonance (LSPR) absorption band wh
9、ich arises from the collective oscillations of the conduction band electrons of Au.The position of the LSPR absorption band of Au NPs in aqueous solution is usually centered at around 520nm.However, the position of the LSPR absorption band of Au NPs can be tuned by changing its particle size or vary
10、ing its surrounding medium.Femtosecond transient absorption spectroscopy has been widely used to investigate the electron relaxation dynamics of Au NPs.Several processes, including electron-electron, electron-phonon, and phonon-phonon interactions, can contribute to the relaxation dynamics of Au NPs
11、.Smith et al.studied the electron relaxation dynamics of 15 nm Au NPs in water and observed time constants of 7 and 400 ps for the electron-phonon and phonon-phonon couplings.Perneret al.measured the relaxation dynamics of 30 nm Au NPs embedded in a sol-gel matrix and found relaxation times of 4 and
12、 200 ps.Inouye et al. recorded the relaxation dynamics of 7.6 nm Au NPs in a Si O2 glass matrix and found time constants of 2.8 and120 ps for its electron-phonon and phonon-phonon relaxation processes.Link et al. studied the dynamics of 15 nm Au NPs embedded in Mg SO4 powder and obtained time consta
13、nts of 8and 200 ps for its electron-phonon and phonon-phonon relaxation processes.It is obvious that the variation of the surrounding medium can change the relaxation dynamics of Au NPs after excitation.However, there is no systematical investigation on how the surrounding environment affects the ul
14、trafast plasmon dynamics of Au NPs in the literature.Besides, it is reported that the semiconductor-Au nanocomposites are of great interest for plasmon-induced photocatalytic applications such as the production of hydrogen, the reduction of thiocyanate, and the oxidation of carbon monoxide.Several r
15、eports have shown that the excited electron of Au NPs after an excitation on its resonance plasmon band can be efficiently transferred into the conduction band of semiconductor nanocrystals.Furubeet al. directly observed plasmon induced electron transfer from 10 nm gold nanodots to Ti O2 nanoparticl
16、es by using femtosecond transient absorption spectroscopy with an IR probe.Wu et al.studied the plasmon-exciton interaction mechanisms in Cd S/Au colloidal quantum confined plexcitonicnanorodheterostructures by transient absorption spectroscopy and found optical excitation of plasmons in the Au tip can lead to hot electron injection into the Cd S rod.To understand how the surrounding medium affect the ultrafast plasmon dynamics of Au NPs and whether the excited e
