摘要
用多光子电离技术结合飞行时间质谱仪对氨与甲醇混合团簇进行了研究,在脉冲激光波长分别为266nm,355nm和532nm条件下,仅在355nm作用下观测到团簇离子,主要的电离产物为质子化的(CH3OH)n(NH3)mH^+(n=0-6,m=0-4)混合团簇离子,且各个序列的离子强度随m的增大而减小。经分析,氨与甲醇混合团簇电离后团簇离子发生内部质子化转移反应是形成质子化团簇离子的主要原因,不同尺寸团簇离子信号强度随电离激光光强变化的光强指数曲线显示,团簇均发生四光子电离过程。应用量化计算,构造了质量数较小的几个团簇离子的可能的空间几何构型,发现二元团簇离子(CH3OH)n(NH3)mH^+是以NH4^+作为内核离子,再通过氢键与其它分子组合而构成团簇离子。
Ammonia-methanol complex clusters have been studied by using multiphoton ionization technique and time-of-flight mass spectrometer. Laser with 266 nm,355 nm and 532 nm wavelengths were used as ionized light source, but protonated cluster ions (CH3OH)n(NH3)mH^+(n = 0-6, m = 0- 4) were observed only when the 355 nm laser was used. The formation of (CH3OH)n(NH3)mH^+ is mainly through proton transfer reaction intra ammonia-methanol clusters ions after laser multiphoton ionization. The curve between laser power and different size cluster ion's intensity indicated that the ionization undergoes a four-photon process. Some possible geometric structures of (CH3OH)n(NH3)mH^+ with relatively small sizes were guessed using ab initio calculation method. The structures show that the NH4^+ trends as the ion's center, and then it combines with other methanol or ammonia molecule to form the final stable complex cluster ions.
出处
《原子与分子物理学报》
CAS
CSCD
北大核心
2007年第5期1049-1054,共6页
Journal of Atomic and Molecular Physics
基金
曲阜师范大学博士科研启动基金
关键词
氨与甲醇混合团簇
多光子电离
飞行时间质谱
质子化团簇
从头算
ammonia-methanol complex clusters, multiphoton ionization, time-of-flight mass spectrum, proto-nated clusters, ab initio calculation