J. Heyrovský Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic.
Phys Chem Chem Phys. 2014 Jan 14;16(2):421-9. doi: 10.1039/c3cp51926k.
We investigate the photodissociation dynamics of freon CF2Cl2 by velocity map imaging at 193 nm. The Cl fragment images are recorded in various expansion regimes corresponding to isolated molecules and molecules in rare gas clusters. The molecular kinetic energy distributions are dominated by a peak at Ekin(Cl) ≈ 0.97 eV corresponding to the direct C-Cl bond dissociation but they also reveal features at lower kinetic energies. Possible mechanisms leading to these slow Cl atoms are discussed. The photodissociation in clusters is investigated in two regimes: (i) small Ar clusters with the CF2Cl2 molecule embedded in approximately one solvation Ar layer; (ii) large Xen, n¯ ≈ 100-500, clusters with embedded CF2Cl2 molecules. In the former clusters we observe caging yielding the Cl fragments with zero kinetic energy and direct exit resulting in fragments with the kinetic energies corresponding to the fragments from isolated molecules. In the latter case (ii) only the caged Cl fragments are observed.
我们通过在 193nm 处进行速度图成像来研究氟利昂 CF2Cl2 的光解动力学。在对应于孤立分子和稀有气体团簇中分子的各种膨胀状态下记录 Cl 碎片图像。分子动能分布主要由一个位于 Ekin(Cl)≈0.97eV 的峰值主导，对应于直接 C-Cl 键解离，但它们也在较低的动能下显示出特征。讨论了导致这些慢 Cl 原子的可能机制。在两种状态下研究了团簇中的光解：（i）嵌入大约一个溶剂化 Ar 层中的 CF2Cl2 分子的小 Ar 团簇；（ii）具有嵌入 CF2Cl2 分子的大 Xen，n¯≈100-500，团簇。在前一种团簇中，我们观察到笼效应导致 Cl 碎片具有零动能，而直接出射导致碎片具有与孤立分子碎片对应的动能。在后一种情况下（ii），仅观察到笼状 Cl 碎片。
