Dynamical Origin of Statistical Behavior in Chemical Reactions

1. (1)我们提出了一种称为“导数态分析”的新技术，使我们能够掌握分子内序列振动能量再分配（IVR）中的层次结构，并将其应用于乙炔分子。首次计算了水的振动高激发态特征态的波函数。我们提出了一种基于fs-laser化学技术检测IVR分层结构的实验方法。(2)在量子力学的基础上提出了不可逆弛豫存在的基本理论，阐明了弛豫速率与分子能级结构之间的联系。我们澄清了在分子碰撞中观察到的随机性的起源。半经典理论表明，当潜在的经典动力学是混沌时，无限数量的经典路径有助于量子力学跃迁振幅。在这种情况下，由于中心极限定理，过渡幅度表现为高斯随机数。这种随机性可能是化学反应中统计行为的一个可能起源。研究了双原子分子在强激光场中的电离。当激光强度超过阈值时，双原子分子表现出抗电离的稳定性。在本研究中，稳定性归因于重叠共振。另一方面，被广泛认为是统计行为的代表性案例的RRKM行为的起源也被证明是重叠共振。强场电离与统计行为通过重叠共振有着深刻的联系，这是强耦合系统的典型现象。

1. Hierarchical Structure of Molecular Dynamics(1) We proposed a novel technique called "derivative state analysis", which enables us to grasp a hierarchical structure in the sequential intramolecular vibrational energy re-distribution (IVR), and applied it to acetylene molecule. Wave function of feature state in vibrationally highly excited state of water was calculated for the first time. We proposed an experimental method, in which a hierarchical structure of IVR can be detected based on the technique of fs-laser chemistry.(2) We presented a basic theory to rationalize the existence of irreversible relaxation on the basis of quantum mechanics, This theory clarifies the connection between the relaxation rate and structure of molecular energy levels.2. We clarified the origin of randomness observed in molecular collisions. Semiclassical theory shows that when underlying classical dynamics is chaotic, an infinite number of classical paths contribute to quantum mechanical transition amplitudes. In that case, the transition amplitudes behave as Gaussian random numbers due to the central limit theorem. This randomness can be one possible origin of statistical behavior in chemical reactions.3. Ionization of diatomic molecules in intense laser fields was investigated. When the laser intensity exceeds a threshold, diatomic molecules exhibit stabilization against ionization. In the present study, the stabilization is ascribable to overlapping resonance. On the other hand, the origin of RRKM behavior, which is widely regarded as a representative case of the statistical behavior, is also shown to be overlapping resonance. Ionization in intense fields and statistical behavior are linked with a profound connection through overlapping resonance, which is a phenomenon typical to strongly-coupled systems.