The far infrared spectra of a series of well-defined gold clusters covered by 2-phenylethanetiolate were studied. The spectra of the cluster are different but the differences are subtle. The Au-S stretching vibrations give rise to bands around 300 cm-1 and below. The relative intensity of these bands changes but they shift only slightly for different clusters. A low-frequency band was identified that is sensitive to the conformation (trans / gauche) of the 2-phenylethanetiolate ligand.