High Resolution IR Studies of Polymolecular Clusters: Micromatrices and Unimolecular Ring Opening

A long Standing goal in the field of cluster research has been to elucidate the transition between the properties of isolated monomer species in the gas phase and the corresponding properties in the condensed phase. One of the most exacting probes of small clusters in this transition region has recently been offered by high resolution spectroscopies, particularly in the microwave and IR region of the spectrum.1—11 Such high resolution studies at rotational resolution can provide detailed information on the distribution of the masses in the cluster, as well as clearly distinguish between various low lying isomeric structures of the same molecular composition. High resolution spectroscopy in the IR also provides the opportunity to study dynamical phenomena such as predissociation,1,12—14 isomerization, and IVR channels that can be accessed by quantum state selected vibrational excitation of the clusters.