Absorption spectra of benzoic acid in the 5-15 THz range
Absorption spectra of benzoic acid were measured between 5 and 15 THz. Hybrid DFT modeling does not reproduce the most intense absorption band at 8.61 THz. The same modeling on benzoic acid dimer reveals that the absorption bands at 8.61 and 12.7 THz occur because of inter-molecular inplane and out-of-plane vibrations of the dimer, respectively. The hydrogen bond length in dimer changes for these modes.