Femtosecond reaction dynamics through

The coherent motion initiated by an excitation pulse can be monitored by variably delayed, ultrashort probe pulses. Since these pulses may also be shorter in duration than the vibrational period, individual cycles of vibrational oscillation can be time resolved and spectroscopy of vibrationally distorted species (and other unstable species) can be carried out. In the first part of this section, the mechanisms through which femtosecond pulses may initiate and probe coherent lattice and molecular vibrational motion are discussed and illustrated with selected experimental results. Next, experiments in the areas of liquid state molecular dynamics and chemical reaction dynamics are reviewed. These important areas can be addressed incisively by coherent spectroscopy on the time scale of individual molecular collisions or half-collisions. 

Femtosecond lasers represent the state-of-the-art in laser technology. These lasers can have pulse widths of the order of 100 fin s. This is the same time scale as many processes that occur on surfaces, such as desorption or diffusion. Thus, femtosecond lasers can be used to directly measure surface dynamics through techniques such as two-photon photoemission [85]. Femtochemistry occurs when the laser imparts energy over an extremely short time period so as to directly induce a surface chemical reaction [86]. 

Norrish type-I reaction, has been studied over the years in extreme detail, with every imaginable physical and theoretical method at hand. Data gathered through studying such reactions on the femtosecond time scale, together with new theoretical work prompted by the dynamics observed, have provided a detailed picture of the processes involved and a fresh perspective on nonconcerted ot-cleavage events. 

Another example where the femtosecond dynamics of bond breaking and bond making was examined is a simple exchange reaction between bromine atom and iodine molecule which goes through a collision complex (intermediate) as follows ... 

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