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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Dissociative Double Ionization of CO2: Dynamics, Energy Levels, and Lifetime
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Dissociative Double Ionization of CO2: Dynamics, Energy Levels, and Lifetime

机译：二氧化碳的离解性双电离：动力学，能级和寿命

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In a kinematically complete experiment on the dissociative double ionization of CO2 by electron impact, spontaneous and metastable decay have been observed via the channel CO_2~(2+) -> CO~+ + O~+. The metastable decay shows a lifetime of 5.8 ± 1.5 mu s. The measured kinetic energy release spectrum of the dissociation shows one broad peak. To understand the observed features, ab initio potential energy surface (PES) for the ground electronic state of CO_2~(2+) was computed using a multireference configuration interaction method and a correlation-consistent polarized-valence quadruple-zeta basis set, for a range of internuclear distances and O-C-O bond angles, and an analytic fit of the PES was obtained. The computed PES clearly indicates the metastability of the dication and yields a barrier height and an asymptotic limit in fair agreement with the reported data, A time-dependent quantum mechanical approach was used to compute the ground vibrational state wave function of CO2 in its ground electronic state. Assuming a Franck-Condon transition, the same function was taken to be the initial wave function at time t = 0 for the time evolution on the fitted PES for the ground electronic state of CO_2~(2+). The autocorrelation function was computed and Fourier transformed to obtain the excitation spectrum. Upon convolution with the instrument resolution function, the kinetic energy release spectrum was obtained, in good agreement with the experimental results, particularly at lower energies. The discrepancies at higher energies are attributed to the noninclusion of the excited states of CO_2~(2+) in the dynamical study.
机译：在一个通过运动对CO2进行离解性双电离的运动学完整实验中，通过通道CO_2〜（2+）-> CO〜+ + O〜+观察到了自发和亚稳态衰变。亚稳态衰变表明其寿命为5.8±1.5μs。离解的测得的动能释放谱显示一个宽峰。为了理解观察到的特征，使用多参考构型相互作用方法和相关一致的极化价四元ζ基集，计算了CO_2〜（2+）基态电子的从头算势能面（PES）。间距和OCO键角的范围，并获得了PES的解析拟合。计算出的PES清楚地表明了药物的亚稳定性，并与报告的数据达成了一致，并产生了障碍高度和渐近极限。采用了时变量子力学方法来计算其地面电子中CO2的地面振动状态波函数州。假设发生了弗兰克-康登跃迁，则在拟合的PES上，当电子为CO_2〜（2+）基态时，在时间t = 0处，相同的函数被视为初始波函数。计算自相关函数并进行傅立叶变换以获得激发光谱。通过与仪器分辨率函数卷积，获得了动能释放谱，与实验结果非常吻合，特别是在较低能量下。在动力学研究中，较高能量的差异归因于未包含CO_2〜（2+）的激发态。

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