TEA CO_2激光波长与功率密度对于气相合成SiC超细粉的影响

The influences of TEA CO 2 laser wavelength and power densities on vapour synthesis of SiC ultrafine powders

用ＴＥＡ ＣＯ２ 激光的不同谱线辐照二甲基二氯硅烷与三甲基氯硅烷气体，只要激光功率密度超过相应的反应阈值，就都可以诱导气相化学反应，制得ＳｉＣ超细粉，其中与物质吸收带重合的入射激光谱线通过多光子吸收机理引发化学反应，而不被基态物质直接吸收的激光谱线则通过级联电离机制引发化学反应。二种反应的机制虽然不同，但由同种原料所得到的产物基本相同。而较高的激光功率密度有利于获得较纯的产物。因此。

Different lines of TEA CO 2 laser were used to irradiate the vapours of dichlorodimethylsilane and chlorotrimethylsilane.Provided the laser power densities were higher than the corresponding reaction thresholds,the vapour chemical reactions were able to be induced and SiC ultrafine powders were synthesized.In the condition of the said experiments,the incident lines which coincided with the absorption bands of the molecules caused chemical reactions via the mechanism of multiphoton absorption,while the lines which were not sbsorbed directly by the molecules in ground vibrational states caused chemical reactions via the mechanism of cascade ionization.From the same material,the products made through the said two different mechanisms were the same on the whole.And the higher laser power densities were helpful to making purer ultrafine powders.So,the ranges of raw materials of these kinds of reactions can be greatly expanded,and no more be limited by the photoabsorption of materials.