Clusters vibrational energy excitation

The processes of energy acquisition, storage and disposal in clusters are of considerable interest in their own right and also for the interpretation of similar processes in finite systems. Consider vibrational energy excitation of an intramolecular vibration of a molecule in a cluster, or of a cluster inter-molecular mode(s), which can be accomplished by collisional excitation, photoselective vibrational excitation, electronic excitation followed by intramolecular radiationless transitions or exciton trapping.178 In charged clusters... 

Remember that it is not the direct energy resonance between the vibrational levels in the two modes that is important. For cluster bond excitation, it is a resonance between the energy of the unoccupied vibrational levels in the weak cluster bond relative to the occupied excited level and quanta of thermal vibrational energy in... 

Cluster state excited Vibrational energy (cm-1) T1VR ... 

O - N vibrational levels of cluster S2 excitation using eq. (5-11). Note that the vibrational energy in the cluster is never sufficient to excite the OH stretch, either directly or indirectly. 

Fig. 26. The vibrational energy, in units of De, of CI2, embedded in a cluster of 125 Ar atoms vs. time, as a probe for a shock front. Examination of the trajectories shows that the molecule is moving towards and has not yet reached the surface. It is excited by collisions with rru e gas atoms which were at the front of the cluster and have already reflected from the rigid surface, back into the cluster. Upper panel Low velocity of impact. A layer of rare gas atoms requires 100 fs to move a distance of one

The prototypical van der Waals molecule infrared photodissociation experiment was originally described by Klemperer in 1974 ( ) He proposed that infrared active constituents of weakly bonded clusters formed in molecular beams be excited with a laser. Since typical vibrational quanta are larger than typical van der Waals bond energies, subsequent intramolecular vibrational energy redistribution would lead to fragmentation that could be detected as beam loss with a mass spectrometer. 

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