Photodissociation Dynamics of Li(NH 3 ) 4 : A Velocity Map Imaging Study
Photodissociation Dynamics of Li(NH 3 ) 4 : A Velocity Map Imaging Study
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Li(NH 3 ) 4 的光解离动力学：速度图成像研究
DOI：
10.1021/jz1015636
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Hopkins W
中科院分区：
文献类型：
--
作者：
Hopkins W
利用光致碎裂光谱和速度图成像相结合的方法研究了碱氨团簇在气相中的光解动力学。Li（NH3）4的电子激发到A → 2T2态导致产生相对缓慢的具有高度内部激发的光碎片，这与Li（NH3）4的内部转换到基态电子态一致，随后是缓慢的统计衰减。在低激发能量下，主要的衰变通道产生Li（NH3）3+ NH3，但在较高能量下，Li（NH3）2是主要的含锂光产物。有证据表明，在出口通道中的障碍，表现为在低动能下观察到的总动能释放（TKER）分布的最大值。对Li（NH3）4→ Li（NH3）3+ NH3过程的TKER分布的建模表明，Li−N键离解能的上限为3750 ± 150 cm− 1，势垒高度为150 ± 50 cm−1。
The photodissociation dynamics of alkali−ammonia clusters in the gas phase have been explored using a combination of photofragmentation spectroscopy and velocity map imaging. Electronic excitation of Li(NH3)4to theÃ2T2state leads to the production of relatively slow photofragments with a high degree of internal excitation, which is consistent with internal conversion to the ground electronic state of Li(NH3)4, followed by slow, statistical decay. At low excitation energies, the dominant decay channel yields Li(NH3)3+ NH3, but at higher energies, Li(NH3)2is the dominant lithium-containing photoproduct. There is evidence of a barrier in the exit channel that manifests itself as a maximum in the total kinetic energy release (TKER) distribution observed at low kinetic energy. Modeling of the TKER distribution for the Li(NH3)4→ Li(NH3)3+ NH3process suggests an upper limit of 3750 ± 150 cm−1for the Li−N bond dissociation energy and a barrier height of ∼150 ± 50 cm−1.