Transient Stimulated Emission Pumping Studies of Photodissociation Dynamics

9304691陈在化学系物理化学计划的这个项目中，加州大学伯克利分校的Y.Chen教授将继续进行一项研究计划，以系统地了解分子内能量转移和化学反应之间的相互作用。为此，他发明的飞秒时间域瞬时受激发射泵浦(TSEP)光谱新技术将应用于臭氧和亚硝酸甲酯两个模型体系，以获得这些物种在光裂解过程中的实时发射光谱。化学反应和解离过程的细节发生在皮秒到飞秒的时间尺度上，这一领域的研究处于当代物理化学的前沿。这些过程提出的问题之一是，激发特定分子振动态的能量如何在分子内重新分配，从而导致特定化学键的断裂或分子重排成不同的构象结构而导致分子解离。与目前使用的其他方法相比，阶梯法具有几个明显的优点：它能够同时提供时间和频率信息，频谱分配明确，并且具有高灵敏度。这使得阶跃方法成为研究多原子体系中能量转移和化学反应的理想工具。***

9304691 Chen In this project of the Physical Chemistry Program in the Chemistry Division, Prof. Y. Chen of the University of California at Berkeley will pursue a program of research to provide a systematic understanding of the interplay between intramolecular energy transfer and chemical reactions. To this end the new technique of femtosecond time-domain Transient Stimulated Emission Pumping (TSEP) spectroscopy invented by him will be applied to two model systems, ozone and methylnitrite to obtain real-time emission spectra during the photofragmentation of these species. %%% The details of chemical reaction and dissociation processes occur at pico- to femtosecond time scales and research in this field is at the forefront of contemporary physical chemistry. Among the questions posed by these processes is how the energy which excites a specific molecular vibrational state redistributes itself within the molecule to result in the dissociation of the molecule by the breaking of a specific chemical bond or in the molecular rearrangement into a different conformational structure. The STEP method possesses several distinct advantages over other techniques currently in use: it is capable of furnishing both time and frequency information, the spectral assignments are unambiguous, and it has high sensitivity. These make the STEP method an ideal tool for studying the energy transfer and chemical reactions in polyatomic systems. ***