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The study of reactions of free radicals by time-resolved infrared semiconductor laser spectroscopy

时间分辨红外半导体激光光谱研究自由基反应

基本信息

批准号：
07454152
负责人：
TANAKA Takehiko
金额：
$ 5.12万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

The aim of this project is to investigate chemical reactions of free radicals generated by ultra-violet laser photolysis by applying highly sensitive time-resolved infrared semiconductor laser spectroscopy. Precursor molecules flowing through an absorption cell of about 2 m length are photolyzed by excimer laser pulses, and generated free radicals are monitored by an infrared semiconductor laser beam, which multipasses a White-type optics. The output of an infrared detector is A/D converted and sent to a personal computer, which performs dual-gated integration and time-profile accumulation.This apparatus was used to observe vibration-rotation spectra in the 5mum region of the FeCO and Fe(CO)_2 radicals generated by ArF excimer laser photolysis of Fe(CO)_5. For FeCo, detailed spectral assignment was accomplished, resulting in precise spectroscopic constants. Absorption lines of Fe(CO)_2 were also identified.These data were utilized for the measurement of decay curves of the FeCO and Fe(CO)_2 radicals, from which rate constants (in units of cm^3 molec^<-1> sec^<-1>) were derived as 1.25(5)*10^<-10> and 1.76(10)*10^<-10> for reactions of the respective radicals with the precursor Fe(CO)_5. Measurement was also made for systems with mixed gases, CO,CS_2, and (CN)_2, and reaction rates with these reactants were determined. The rate of the reaction with CO is 1.48(5)*10^<-11> for FeCo and 1.77(21)*10^<-11> for Fe(CO)_2. The radicals react with CO at an order of magnitude slower rate than with the precursor. The reaction rate with CS_2 is 2.87(24)*10^<-10> for FeCO and 1.69(15)*10^<-10> for Fe(CO)_2. FeCO reacts with (CN)_2 at a rate of 2.19(22)*10^<-10> and Fe(CO)_2 at 1.96(17)*10^<-10>. These reaction rates are comparable with those with the precursor.

本项目的目的是应用高灵敏度的时间分辨红外半导体激光光谱学研究紫外激光光解产生的自由基的化学反应。前体分子流过约2米长的吸收池的受激准分子激光脉冲的光解，并产生的自由基的监测由红外半导体激光束，其中多通怀特型光学。红外探测器的输出信号经A/D转换后送入微机，微机进行双选通积分和时间剖面积累，用该装置观测了ArF准分子激光光解Fe（CO）_5产生的FeCO和Fe（CO）_2自由基在5 μ m区域的振转光谱。对于铁钴，详细的光谱分配完成，从而在精确的光谱常数。利用这些数据测量了FeCO和Fe（CO）_2自由基的衰减曲线，并由此导出了它们与前驱体Fe（CO）_5反应的速率常数<-1><-1>分别为1.25（5）× 10 ~（-5）<-10>和1.76（10）× 10 ~<-10>（-5）。还对CO、CS_2和（CN）_2混合气体体系进行了测量，测定了它们的反应速率。与CO的反应速率为FeCo的1.48（5）× 10 ~<-11>（-1），Fe（CO）_2的1.77（21）× 10 ~<-11>（-1）。自由基与CO的反应速率比与前体的反应速率慢一个数量级。FeCO和Fe（CO）_2与CS_2的反应速率分别为2.87（24）× 10 ~ 3<-10>和1.69（15）× 10 ~ <-10>3。FeCO与（CN）_2的反应速率为2.19（22）× 10 ~<-10>（-1），与Fe（CO）_2的反应速率为1.96（17）× 10 ~（-1）<-10>。这些反应速率与前体的反应速率相当。