Dynamics of Polyatomic Molecules in Intense Laser Fields

韦恩州立大学的Robert Levis得到了实验物理化学计划的支持，其研究重点是多原子分子与飞秒持续时间的强近红外激光脉冲的相互作用。本计画的目标是阐明强激光与多原子分子间的耦合机制，了解强激光电离过程中导致解离的因素，以及发展辐射分子相互作用的时间相关图像。 光电子能谱和飞行时间质谱测量将描绘各类分子的耦合机制，揭示电离和解离概率以及电子动能分布的实验观测值。 电子和核自由度之间的能量分配将由碎片离子动能分布和电子-离子符合实验确定。 最后，时间分辨实验将提供分子在强激光场中演化的详细图像。 极强的光诱导分子的行为与相同颜色但较弱的光诱导分子的行为大不相同。 强光导致不寻常的离解和电离过程的能力正在帮助开发新的光学方法，如高次谐波发生装置和X射线激光。这些研究的结果在生物质谱的通用电离方法、化学反应动力学的新检测方法和相干控制方法中具有潜在的应用。

Robert Levis of Wayne State University is supported by the Experimental Physical Chemistry Program for research that focuses on the interaction of polyatomic molecules with intense near-infrared laser pulses of femtosecond duration. The objectives of this project are to elucidate the coupling mechanism between an intense laser and a polyatomic molecule, to understand the factors leading to dissociation during intense laser ionization, and to develop a time-dependent picture of the radiation molecule interaction. Photoelectron spectroscopy and time-of-flight mass spectrometry measurements will delineate the coupling mechanisms for various classes of molecules, revealing the experimental observables of ionization and dissociation probability and the electron kinetic energy distributions. Energy partitioning between electronic and nuclear degrees of freedom will be determined from fragment ion kinetic energy distributions and electron-ion coincidence experiments. Finally, time-resolved experiments will provide a detailed picture of the evolution of a molecule in an intense laser field. Extremely intense light induces far different behaviors in molecules than does the same color, but weaker light. The ability of intense light to result in unusual dissociation and ionization processes is assisting in the development of novel optical methods such as high harmonic generation devices and x-ray lasers. Outcomes from these studies have potential applications in a universal ionization method for biological mass spectrometry, new detection methods for chemical reaction dynamics, and methods for coherent control.