Frequency shifts in infrared spectra of ethylene clusters

摘要

Based on structure calculations of small ethylene (C2H4)nclusters published previously lsqb;R. Alrichsetal., Z. Phys. D15, 341 (1990)rsqb;, shifts and splittings of the fundamental excitation frequency of the ngr;7mode are calculated for the dimer, trimer, and tetramer. Using a first order perturbation approach, we find blue shifts in the order of 1ndash;3 cmminus;1which compare well with experimental findings. It is shown that the shifts are approximately independent of the cluster size and of the isomeric structure (ringlike or chainlike) of the ethylene complexes.