Collisional energy transfer, intramolecular vibrational relaxation and unimolecular reactions
Collisional energy transfer, intramolecular vibrational relaxation and unimolecular reactions
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碰撞能量转移、分子内振动弛豫和单分子反应
DOI：
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发表时间：
1997
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通讯作者：
Ian W. M. Smith
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文献类型：
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作者：
Ian W. M. Smith
对（a）非常高压下的缔合反应和（b）能够形成强化学键的物质之间的振动弛豫的实验证实了这样的假设：对于同一化学体系，这两个速率本质上是相同的，都反映了碰撞复合物的形成速率。审查这些测量的结果。随后，讨论碰撞伙伴之间的吸引力较弱的情况。在这些情况下，振动弛豫率似乎对应于复合物形成的下限，因为在涉及振动激发物质的碰撞中形成的复合物可能会在复合物内的分子内振动弛豫使位于最初激发的振动中的能量随机化之前重新解离。讨论了许多示例，CH+N2、NO+NO2、NO+NO、几种离子分子系统以及一些涉及 OH 和不饱和分子的系统，其中似乎正在发生这种行为。需要强调的是，无论是否观察到限制性的“强吸引力”行为，都将取决于碰撞物质的能量，因此在热实验中取决于温度。最后，对通过碰撞复合体进行的碰撞中振动能量传递的状态到状态方面进行了一些考虑。
Experiments on (a) association reactions at very high pressures and (b) vibrational relaxation between species capable of forming a strong chemical bond have confirmed the hypothesis that, for the same chemical system, these two rates are essentially the same, both reflecting the rate of formation of collision complexes. The results of these measurements are reviewed. Subsequently, cases are discussed where the attraction between the collision partners is less strong. In these cases, it seems that the vibrational relaxation rate corresponds to a lower limit for complex formation, as complexes formed in collisions involving a vibrationally excited species may redissociate before intramolecular vibrational relaxation within the complex randomises the energy located in the initially excited vibration. A number of examples, CH+N2, NO+NO2, NO+NO, several ion–molecule systems and several involving OH and unsaturated molecules, where this behaviour seems to be occurring are discussed. It is emphasised that, whether or not the limiting, ‘strong attraction’, behaviour is observed will depend on the energy of the colliding species and therefore, in thermal experiments, on temperature. Finally, some consideration is given to the state-to-state aspects of vibrational energy transfer in collisions proceeding via collision complexes.