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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Ultrafast Chemistry of Nanoenergetic Materials Studied by Time-Resolved Infrared Spectroscopy: Aluminum Nanoparticles in Teflon
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Ultrafast Chemistry of Nanoenergetic Materials Studied by Time-Resolved Infrared Spectroscopy: Aluminum Nanoparticles in Teflon

机译：时间分辨红外光谱法研究的纳米能材料的超快化学：铁氟龙中的铝纳米颗粒

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Ultrafast mid-infrared (IR) spectroscopy is used to monitor chemical reactions initiated by flash-heating a nanoenergetic material consisting of 30 nm diameter Al nanoparticle fuel in a Teflon~(AF) oxidizer. Teflon~(AF) is a copolymer of tetrafluoroethylene (TFE) and 2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole (dioxole), so Al can react with several different moieties. Transitions associated with CF_2 stretching of TFE or CFO stretching or CF_3 stretching of dioxole were monitored. The reactions of Al with CFO occurred with time constant (k_1)~(-1) = 50 (±20 ps); reactions of Al with CF_2 or CF_3 were more than 10 times slower, (k_2)~(-1) = 0.7 (±0.05 ns). An interesting frequency oscillation is seen in the 1148 cm~(-1) band, where the peak frequency undergoes a time-dependent shift from 1148 to 1155 cm~(-1) and then back to 1148 cm~(-1). Due to the coincidence of CFO and CF_2 stretching transitions, this band in the copolymer represents an amalgamated vibration with amplitude on both TFE and dioxole. As concentration is varied from pure dioxole to pure TFE, the band blue-shifts. A kinetic scheme and a model for the concentration dependence of the amalgamated vibration frequency are developed, which show that the frequency oscillation is a consequence of the arrangement of reactants on the nanoscale, which creates two types of oxidizer. The type adjacent to the Al nanoparticle is in a region of high local fuel concentration, while the other type is too distant from the fuel to react.
机译：超快中红外（IR）光谱用于监测通过在Teflon〜（AF）氧化剂中快速加热包含30 nm直径的Al纳米颗粒燃料的纳米高能材料引发的化学反应。铁氟龙（AF）是四氟乙烯（TFE）和2,2-双（三氟甲基）-4,5-二氟-1,3-二恶唑（dioxole）的共聚物，因此Al可以与几个不同的部分反应。监测与TFE的CF_2拉伸或二恶唑的CFO拉伸或CF_3拉伸相关的转变。 Al与CFO的反应时间常数为（k_1）〜（-1）= 50（±20 ps）。 Al与CF_2或CF_3的反应要慢10倍以上，（k_2）〜（-1）= 0.7（±0.05 ns）。在1148 cm〜（-1）波段中观察到有趣的频率振荡，其中峰值频率从1148到1155 cm〜（-1）随时间变化，然后又回到1148 cm〜（-1）。由于CFO和CF_2拉伸转变的同时发生，共聚物中的这一带代表了TFE和二恶唑上振幅均增大的混合振动。当浓度从纯二氧杂环己烷变化到纯TFE时，能带发生蓝移。建立了动力学模型和混合振动频率的浓度依赖性模型，结果表明频率振荡是反应物在纳米级上排列的结果，产生了两种类型的氧化剂。与Al纳米颗粒相邻的类型在高局部燃料浓度的区域中，而另一种类型与燃料的距离太远而无法反应。

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