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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >I~*(~2P_(1/2)) and Cl~*(~2P_(1/2)) Production from Chloroiodobenzenes in the Ultraviolet
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I~*(~2P_(1/2)) and Cl~*(~2P_(1/2)) Production from Chloroiodobenzenes in the Ultraviolet

机译：I〜*（〜2P_（1/2））和Cl〜*（〜2P_（1/2））在紫外线下由氯代苯生成

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摘要

The relative quantum yields of I~*(~2P_(1/2)) and Cl~*(~2P_(1/2)) production,phi*(I) and phi~*(C1),respectively,have been measured at four different ultraviolet excitation wavelengths,e.g.,222,236,266,and 280 nm in the photodissociation of o-,m-,and p-chloroiodobenzenes.The measured I~* and Cl~* quantum yields are,with some exceptions,higher than those obtained,respectively,from iodobenzene and chlorobenzene,at the same wavelengths.While at most wavelengths the major fraction of the iodine atoms is produced in the excited state,the opposite is true for the chlorine atoms.Both direct and indirect dissociation pathways are involved in the production of I~* atoms whereas Cl~* is produced only by indirect pathways since direct excitation of the sigma~*(C-Cl) <- _n(Cl) transition is not possible at these wavelengths.The halogen atom in the ortho position is found to be most effective in enhancing the yield of the other spin-orbit excited halogen atom in the photolysis.While the nature of the initial transition,the extent of intersystem crossing in the excited states and the exit channel effects need to be considered in interpreting the quantum yield results,some factors seem to be more effective in influencing the final outcome.Induced dipole-induced dipole and quadrupole- quadrupole interactions between the two halogen atoms (I and Cl in this case) seem to play an important role in the exit channel dynamics.These electrostatic interactions facilitate the intersystem transfer in the excited state and subsequent production of the spin-orbit excited halogen atoms.
机译：分别测量了I〜*（〜2P_（1/2））和Cl〜*（〜2P_（1/2））产生的相对量子产率phi *（I）和phi〜*（C1）在邻，间和对氯碘苯的光解中，在四个不同的紫外激发波长（例如222,236,266和280 nm）处。测得的I〜*和Cl〜*量子产率（除某些例外）高于所获得的分别从相同波长的碘代苯和氯代苯得到。虽然在大多数波长下，碘原子的主要部分是在激发态下产生的，但氯原子却是相反的。 I〜*原子的产生，而Cl〜*仅通过间接途径产生，因为在这些波长下不可能直接激发sigma〜*（C-Cl）<-_n（Cl）跃迁。在光解过程中，发现最有效地提高其他自旋轨道激发的卤原子的收率。在初始跃迁中，在解释量子产率结果时，需要考虑激发态中系统间交叉的程度以及出口通道的影响，某些因素似乎在影响最终结果方面更为有效。两个卤素原子（本例中为I和Cl）之间的四极相互作用似乎在出口通道动力学中起着重要作用，这些静电相互作用促进了激发态下的系统间转移以及自旋轨道激发的卤素原子的后续生成。

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