State-Resolved and Bond-Selected Bimolecular Chemistry

Fleming Crim教授得到了实验物理化学计划的资助，他观察高振动激发的多原子分子的双分子反应，并利用这些状态的特殊性质来直接控制化学反应的过程。其目的是开发和测试控制较大分子中键断裂的方案，并进行完全量子态分辨的测量，这些测量可以与理论动力学计算进行比较。该技术的实质是激发多原子分子中的孤立振动，并通过与反应原子(如H或O)的碰撞将该振动转换为反应坐标。要研究的反应包括HCN、乙炔、氨、甲烷、丙烷和甲醇，使用受激发射泵浦和真空紫外光诱导荧光等技术。在这项研究中，多原子分子和原子之间的化学反应过程是利用振动激发直接控制的，这是基于从反应物到产物的几何变化需要键的伸展和断裂这一事实。在大气化学、燃烧和等离子体中，涉及带电分子碰撞的反应是中心。

Professor Fleming Crim is supported by a grant from the Experimental Physical Chemistry Program to observe bimolecular reactions of highly vibrationally excited polyatomic molecules and to exploit the special nature of these states to directly control the course of chemical reactions. The object is to develop and test out schemes to control bond breaking in larger molecules and to make fully quantum-state-resolved measurements which can be compared with theoretical dynamical calculations. The essence of the technique is to excite an isolated vibration in a polyatomic molecule and to turn that vibration into a reaction coordinate by a collision with a reactive atom such as H or O. Reactions to be studied involve HCN, acetylene, ammonia, methane, propane, and methanol, using techniques such as stimulated emission pumping and laser-induced-fluorescence at vacuum ultraviolet wavelengths. %%% In this research the course of a chemical reaction between a polyatomic molecule and an atom is directly controlled by making use of vibrational excitation, based on the fact that the geometry change that occurs in going from reactants to products requires the stretching and breaking of bonds. Reactions involving collisions of energized molecules are central in atmospheric chemistry, combustion, and plasmas.