Al_n^+(n=2～13)团簇分裂机理的计算

Calculation of decomposition mechanism of Al_n^+(n=2～13) clusters

基于Aln+m+团簇分离方式主要以离解出中型或带电单Al原子为主的实验结果,采用线性同步转变(LST)和二次同步转变(QST)方法考察了Aln+m+ (n+m≤13) 团簇在双分模式下的不同分裂过程,并通过分裂吸收热ΔHR-P和分裂激活能ΔER-T等的计算,在能态结构上分析了Aln+(n=2~13)团簇的分裂路径及其机理。结果表明: Aln+ (n=2~13)团簇以分裂出电中性或带电Al原子模式吸热ΔHR-P和所需分裂激活能ΔER-T最少,而分裂成原子数相差较小的两个较大团簇所需裂解能量最多,因此,Aln+ (n=2~13)团簇主要以Aln+ →Al+ Aln-1+或Aln+→Al++ Aln-1路经裂解。

Based on the experimental result of Al（n＋m）^＋ clusters decomposed by means of a isolated Al atom or cation, the disassociation route and mechanism of Al（n＋m）^＋（n＋m≤13） clusters in the Aln^＋＋Alm （n=1-12, m=1-12） mode were investigated by linear synchronous transit （LST） and quadratic synchronous transit （QST） method. Several parameters, such as the ionization potential, the endothermic reaction heat △HR-P and the dissociation barrier energy △ER-T of Al（n＋m）^＋（n＋m≤13） clusters were calculated. Comparison of △HR-P and AER.T requested in the disassociation route reveals the least energy of a isolated Al atom or cation from the Al（n＋m）^＋ clusters is related to bigger △HR-P and △ER-T values, while a big cluster decomposites into two small clusters. The energetics difference between routes should be responsible for the preferential route of dissociation of A Aln＋^＋（n=2～13） clusters in terms of Aln^＋→Al＋Al（n-1）^＋ or Aln^＋→Al＋Al（n-1）