Vibrational frequency shifts and thermodynamic stabilities of (HF)n isomers (n=4–8)

Based on the spectroscopic data available for the HF dimer and trimer and taking into account the cooperativity effect, the force fields of larger (HF)n clusters (n=4–8) have beeen determined for various isomeric structures and used to calculate the frequency shifts for the stretching vibrations. The comparison with recent experimental results, obtained with size selection, suggests that tailed ring structures (i.e. symmetric rings with additional HF units attached to them) might play an important role in the cluster distribution in expansion-cooled molecular beams. Thermodynamic calculations show that tailed ring structures have comparably high stabilities.