摘要
NH_3/He混合气在超声分子束中形成分子簇,在427～442nm可见区用激光进行多光子电离,用飞行时间质谱仪检测到氨分子簇离子,最大的合17个N原子。除了质子化离子(NH_3)_nH^+之外,还有(NH_3)_n^+(NH_3)_nH_2^+和(NH_3)_(n-1)NH_2^+。离子强度的分布在较短波长和较长波长处有所不同。本文讨论了以上团簇离子形成的可能机理。
Multiphoton Ionization (MPI) of ammonia clusters produced in a supersonic molecular beam has been carried out in laser wavelengths of 427-442 nm. The cluster ions measured by TOF mass spectrometer contained N atom numbers up to 17. Aside from protonated (NH_3)_nH^+, we have observed unprotonated (NH_3)_n^+, and other two kinds of ions (NH_3)_nH_2^+ and (NH_3)_(n-1)NH_2^+ as well. The mass spectrum is more closc to that of electron impact rather than that of UV MPI. Ion intensity distribution is somewhat different at shorter and longer wavelengths. Possible mechanism of the cluster ion formation is discussed.
