直接激光气化法产生气相MnCl_2团簇的研究

Mechanism of Production of MnCl 2 Cluster by Laser Vaporization

报道了５３２ｎｍ激光气化ＭｎＣｌ２·４Ｈ２Ｏ固体产生气相团簇（ＭｎＣｌ２）ｎＭｎ＋、（ＭｎＣｌ２）ｎＭｎＣｌ＋、（ＭｎＣｌ２）ｎＣｌ－（ｎ＝１～１２），以及溶剂化的团簇ＭｎＣｌ＋（ＭｎＣｌ２）ｎ（Ｈ２Ｏ）ｍ（ｎ＝１～７，ｍ＜６）的机理，通过用飞行时间质谱考察团族的尺寸大小与激光能量、激光与脉冲加速电场之间延迟时间等的关系。认为这些团簇是通过气相化学反应逐步生长的，并提出了正负团簇离子产生的可能通道。通过比较正负团簇系列种类和强度，提出这些团簇可能具有类链状结构。结果表明，合适地控制激光能量、激光光斑，选择合适的样品，直接气化法也能产生大的团簇。

Cluster ions(MnCl 2) nMn +,(MnCl 2) nMnCl +,(MnCl 2) nCl -,n=1～12,and water solvated cluster ions(MnCl 2) n(H 2O) mMnCl +,n=1～7,m=1～5 were produced by 532nm laser vaporization of MnCl 2·4H 2O solid pellet and studied by time-of-flight mass spectrometry We found that lager cluster can only be detected under a short range of laser energy and delay time between laser and pulsed electric acceleration voltage All the observed information indicates these cluster ions are produced by a gas-phase ion-molecule reaction and aggregation of gas phase Mncl 2,and some of the reasonable formation pathways of the observed cluster ions are proposed By comparison the intensity pattern of positive and negative cluster ions,we proposed a chain-like structures for the observed cluster ions The experiment results show that by careful control the laser energy,laser size,cluster can also be obtained by direct laser vaporization of some compounds without carrying gas.