Examination of Silver Nanoparticle Fabrication by Pulsed-Laser Ablation of Flakes in Primary Alcohols

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• 作者：Daniel Werner ; Shuichi Hashimoto ; Takuro Tomita ; Shigeki Matsuo ; Yoji Makita
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：February 7, 2008
• 年：2008
• 卷：112
• 期：5
• 页码：1321 - 1329
• 全文大小：493K
• 年卷期：v.112,no.5(February 7, 2008)
• ISSN：1932-7455

文摘

This paper describes the formation and subsequent behavior of silver nanoparticles (NPs) observed by opticalspectra, atomic force microscopy, and transmission electron microscopy in primary alcohols by nanosecondpulsed-laser irradiation (1064 and 532 nm, typically at 1 J/(cm² pulse)) of silver flakes. Effects of the carbonchain length of the solvents and the irradiation atmosphere of the solutions on the Ag NP formation wereinvestigated. The effect of alcohol chain length in aerated solutions can be described as follows: (1) in short-chain alcohols such as methanol and ethanol, the NPs are extremely unstable and easily settled down to formprecipitates by centrifugation treatment; (2) very stable NPs are formed with an appreciably smaller particlesize distribution in alcohols with chain lengths from C-3 to C-5 than in alcohols with longer chain lengththan C-5; (3) the yield of NPs is dependent on the alcohol chain length. On the other hand, the yield of NPsis greater in Ar- and N₂-saturated solutions than in aerated solutions. Additionally, the yield is similar regardlessof the chain length, with smaller size distributions than those in air-equilibrated solutions. Oxygen moleculesdissolved in the solvents are responsible for these observations. The oxygen effect consists of two parts: (1)the scavenging of electrons generated by the plasma formation and thermionic emission due to extremelyhigh temperature under the ablation condition; (2) the formation of an oxide layer on the surface of particlesthat hampers further growth processes to form NPs. Furthermore, we observed the formation of string segmentsin evacuated ethanol due to coagulation and coalescence of bare metal particles, giving rise to the splittingof the plasmon band. Thus we demonstrated that the systematic change in the solvent and irradiation atmospherecan control the particle size and size distribution. The present findings may add a new aspect to better manipulateNP fabrication based upon the laser ablation method.