Effects of Molecular Interactions on Coherent Electric Quadrupole Radiation Processes
Helen S. Freedhoff · Physical Review A · 1972
The theory of the line shape in coherent electric quadrupole absorption and emission processes involving $N$ interacting molecules is developed, both quantum mechanically and with the use of a classical model. The theory is applied to small clusters and to linear chains of molecules. As in the dipole case, the effects of the interaction include in general a splitting of each molecular transition line into a number of components, a shift of each component from the molecular transition frequency, and a broadening or narrowing of each component relative to the width of the molecular line.