Hyper-Rayleigh Scattering from Gold Nanorods

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• 作者：Yara El Harfouch ; Emmanuel Benichou ; Franck Bertorelle ; Isabelle Russier-Antoine ; Christian Jonin ; No?lle Lascoux ; Pierre-Fran?ois Brevet
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：January 9, 2014
• 年：2014
• 卷：118
• 期：1
• 页码：609-616
• 全文大小：362K
• ISSN：1932-7455

文摘

The first hyperpolarizability of gold nanorods with dimensions 64 脳 24 脳 24 nm³ is determined by hyper-Rayleigh scattering (HRS) at the fundamental wavelength of 784 nm. For cetyltrimethylammonium bromide (CTAB)-capped nanorods in aqueous solutions, the measured value is 尾_Au鈥揅TAB = (0.88 卤 0.02) 脳 10^鈥?4 esu. For the same nanorods after phase transfer into chloroform with replacement of the CTAB capping layer by a dodecanethiol or an octadecanethiol layer, the measured value is only 尾_Au鈥揅12 = (0.22 卤 0.02) 脳 10^鈥?4 esu and 尾_Au鈥揅18 = (0.20 卤 0.02) 脳 10^鈥?4 esu using the newly determined water hyperpolarizability reference of 尾 = 0.087 脳 10^鈥?0 esu. In both cases, it is demonstrated through polarization-resolved HRS that the major contribution to the SHG response from these centrosymmetric nanoparticles stems from the surface as a breaking of the centrosymmetry, similarly to what is observed for gold nanospheres. Besides, the reduced hyperpolarizability measured for the gold nanorods with the thioalkane capping layer is attributed to the bond formed between the gold surface atoms and the sulfur atom of the capping layer, similarly to the case of gold nanospheres, too.