C_2H_2和C_4H_2放电产生碳氢团簇(C_nH_m)的质谱研究

Study on mass spectra of hydrocarbon clusters(C_nH_m) from C_2H_2 and C_4H_2 discharge plasma

利用分子束质谱结合激光电离技术检测乙炔(C2H2)和丁二炔(C4H2)不同碳氢配合物放电等离子体过程产生的中性碳氢团簇(CnHm),比较不同前驱物对碳氢团簇质谱分布和质谱强度的影响.实验结果表明,由C2H2和C4H2放电产生的碳氢团簇存在相似的质谱峰分布,即在碳原子个数不大于8时,偶数碳的碳氢团簇CnHm在质谱图上呈现的峰比奇数碳的碳氢团簇强;当碳原子个数大于9时,不同前驱物放电产生碳氢团簇CnHm在质谱图上均出现偶数和奇数碳氢团簇的相间分布,并随着碳原子个数的增加,碳氢团簇质谱峰的强度总体呈现减弱趋势.另外由于C2H2和C4H2结构不同,稳定性存在差异,在放电条件下产生的碎片不同,合成碳氢团簇的质谱峰在强度上存在差异.

Hydrocarbon clusters （Cn Hm） from C2 H2 and C4 H2 discharge plasma have been studied by molecular-beam time-of-flight mass spectrometry with laser ionization technology. The result shows that the distributions of mass peaks CnHm, from C2 H2 and C4 H2 discharge plasma are similar. When n≤8, CnHm signals with the even-n group are strong. The alternation of C, Hm signals with even/odd n appears for n≥9 with the odd-n groups having stronger signals. The CnHm, mass spectrometric sig- nals generally become weak with increasing n. The signals on mass spectra of Cn Hm, from C2 H2 are weaker than that from C4 H2 due to their different structures and stabilities.