Martín-Sómer Ana, Yáñez Manuel, Gaigeot Marie-Pierre, Spezia Riccardo
Departamento de Química, Facultad de Ciencias, Módulo 13. Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC. Cantoblanco , E-28049 Madrid, Spain.
J Phys Chem A. 2014 Nov 20;118(46):10882-93. doi: 10.1021/jp5076059. Epub 2014 Nov 5.
By combining chemical dynamics simulations and RRKM statistical theory we have characterized collision induced dissociation (CID) mechanisms of M(formamide) ions (M = Ca, Sr) at different timescales, from few femtoseconds to microseconds. Chemical dynamics simulations account for the short-time and dynamically driven reactivity, such as impulsive collision mechanism for formamide neutral loss. From the simulations, we also got the amounts of energy transferred during the collision and, especially important, the vibrational and rotational energy distributions of the ions that did not react during the simulation time length of 2.5 ps. These internal energy distributions were in turn used in combination with RRKM theory to estimate the rate constants of the possible reactive pathways. Hence, we performed a statistical analysis of the CID dynamics accounting for the long-time and statistical reactivity (i.e., through an IVR mechanism). This multiscale approach allowed us to account for all the products observed in the CID experimental spectra of Ca(formamide) and Sr(formamide) doubly charged cations, as well as the differences between them.
通过结合化学动力学模拟和RRKM统计理论，我们在从飞秒到微秒的不同时间尺度上，对M(甲酰胺)离子（M = Ca、Sr）的碰撞诱导解离（CID）机制进行了表征。化学动力学模拟考虑了短时间内由动力学驱动的反应性，例如甲酰胺中性丢失的脉冲碰撞机制。通过模拟，我们还得到了碰撞过程中转移的能量，尤其重要的是，在2.5皮秒的模拟时间长度内未发生反应的离子的振动和转动能量分布。这些内能分布反过来又与RRKM理论结合使用，以估计可能反应途径的速率常数。因此，我们对CID动力学进行了统计分析，考虑了长时间的统计反应性（即通过内禀反应坐标机制）。这种多尺度方法使我们能够解释在Ca(甲酰胺)和Sr(甲酰胺)双电荷阳离子的CID实验光谱中观察到的所有产物，以及它们之间的差异。
