Reaction rates femtochemistry

The emphasis in Part 1 has been on an introduction to chemical kinetics and the analysis of reaction mechanism. A main theme has been to describe how experimental measurements of reaction rates, both as a function of concentration and temperature, can provide information on the mechanisms of chemical reactions. The coverage has been wide-ranging from fundamental well-established concepts to leading-edge research in femtochemistry. 

Important classes of chemical reactions in the ground electronic state have equal parity for the in- and out-going channels, e.g., proton transfer and hydride transfer [47, 48], To achieve finite rates, such processes require accessible electronic states with correct parity that play the role of transition structures. These latter acquire here the quality of true molecular species which, due to quantum mechanical couplings with asymptotic channel systems, will be endowed with finite life times. The elementary interconversion step in a chemical reaction is not a nuclear rearrangement associated with a smooth change in electronic structure, it is aFranck-Condon electronic process with timescales in the (sub)femto-second range characteristic of femtochemistry [49],... 

In the remaining Sections of Part 1 we turned to a more theoretical view of chemical kinetics. In Section 7 we looked again at elementary reactions and examined models of bimolecular reactions in both the gas phase and solution. The developing area of femtochemistry was also introduced. Finally, in Section 8, we moved to a more extended discussion of reaction mechanism. We considered the type of evidence that is needed to establish that a reaction is composite and, importantly, how the concept of a rate-limiting step is used to simplify the analysis of a reaction mechanism. The latter provides a means of deriving a predicted rate equation that can be compared with experiment. 

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