Collisional Energy Conversion in Polyatomic Molecules

印第安纳大学的Charles Parmenter得到了实验物理化学项目的资助，他在气相中进行了从大的多原子分子到原子和双原子分子的振动和旋转能量转移的实验。利用激光抽运产生具有态对态分辨率的内部激发，分散荧光沿着重要的能量传递通道进行。研究的体系有：(1)激光定向乙二醛和氘化甲醛与氢、氦、氘的碰撞，研究取向的影响；(2)气体的碰撞活化/失活，如大分子的氩气（对二氟苯是一个最好的例子），其中有足够的内能发生离解和异构化。后一项研究涉及测定高激发分子的绝对反应截面，这在以前是不可能的。提出的研究将对我们理解能量如何从大分子转移到其他原子和小分子，特别是内能转化为运动能产生重大影响。这些复杂和非常基础的研究将确定过程的效率，以及能量传递过程如何受到取向的影响。它们与与大气化学有关的高度激发态有关。

Charles Parmenter of Indiana University is supported by a grant from the Experimental Physical Chemistry Program to perform experiments on vibrational and rotational energy transfer from large polyatomic molecules to atoms and diatomic molecules in the gas phase. Laser pumping will be used to produce the internal excitation with state to state resolution while dispersed fluorescence will follow the important energy transfer channels. The systems to be studied are: (1) collisions of laser aligned glyoxal and deuterated formaldehyde with hydrogen, helium and deuterium to investigate the effects of orientation; and (2) collisional activation/deactivation by gases such as argon of large molecules (p-difluorobenzene is a prime example) where there is enough internal energy for dissociation and isomerization to occur. This latter study involves the determination of absolute reaction cross sections for highly excited molecules which has not previously been possible.The proposed studies will have a major impact on our understanding of how energy is transferred from large molecules to other atoms and smaller molecules, especially the conversion of internal energy into energy of motion. These sophisticated and very fundamental studies will determine the efficiency of the processes and how the energy transfer process is influenced by orientation. They have relevance to highly excited species associated with atmospheric chemistry.