Analysis of intermolecular vibrational modes in organic compounds using two-dimensional terahertz correlation spectroscopy

In this study, the terahertz (THz) absorption spectra of tris(8-quinolinolato) aluminum were measured during 100-300 K. The temporal changes in the absorption spectra were analyzed using two-dimensional correlation spectroscopy (2DCOS). By comparing the cross peaks corresponding to the intermolecular vibrational modes, we concluded that the high-frequency band could be attributed to the vibration of the structure and the low-frequency band to the vibration between the structures. The exact frequencies of the overlapping vibrational bands and their assignments provide a new means to inspect the thermal behavior of the intermolecular vibrational modes.