论文标题
关于中性和刚性多原子分子的电子波袋中相干性的保存
On the preservation of coherence in the electronic wavepacket of a neutral and rigid polyatomic molecule
论文作者
论文摘要
我们提供了各种类型的还原模型，包括吡嗪分子的五种振动模式和三个电子状态，以研究刚性和中性系统中电子相干性的寿命。使用在基态（1 1 A g）处的超快光学泵浦，我们准备了两个明亮的激发态的相干叠加，即1 1 B 2U和1 1 B 1U，并揭示了核运动对保存激光脉冲诱导的电子相干性的影响。更具体地说，考虑了两个方面：势能表面的呼吸道和过渡偶极矩（TDM）相对于核坐标的依赖性。为此，我们通过进行三个近似值来定义一个理想的模型：（i）仅五个完全对称模式移动，（ii），（ii）对应于未偶联的谐波振荡器，以及（iii）从地面电子状态到两个明亮状态的TDMS是恒定的（Franck-Condon近似）。然后，我们首先考虑了非谐度性的效果，第二，TDM的坐标依赖性（一阶Herzberg- Teller贡献），第三。我们使用量子动力学的详细数值研究证实了电子连贯性的长期复兴，即使对于最现实的模型也是如此。
We present various types of reduced models including five vibrational modes and three electronic states for the pyrazine molecule in order to investigate the lifetime of electronic coherence in a rigid and neutral system. Using an ultrafast optical pumping in the ground state (1 1 A g ), we prepare a coherent superposition of two bright excited states, 1 1 B 2u and 1 1 B 1u , and reveal the effect of the nuclear motion on the preservation of the electronic coherence induced by the laser pulse. More specifically, two aspects are considered: the anharmonicity of the potential energy surfaces and the dependence of the transition dipole moments (TDMs) with respect to the nuclear coordinates. To this end, we define an ideal model by making three approximations: (i) only the five totally symmetric modes move, (ii) which correspond to uncoupled harmonic oscillators, and (iii) the TDMs from the ground electronic state to the two bright states are constant (Franck-Condon approximation). We then lift the second and third approximations by considering, first, the effect of anharmonicity, second, the effect of coordinate-dependence of the TDMs (first-order Herzberg- Teller contribution), third, both. Our detailed numerical study with quantum dynamics confirms long-term revivals of the electronic coherence even for the most realistic model.
