Benzene and methanol make a minimum boiling point homogeneous binary azeotrope with the mole ratio 2:3. Some characteristic vibrational modes, as well as 1H NMR signals change due to the azeotrope formation. The extend of interaction of these molecules causes significant changes on some vibrational modes involved, and 1HNMRsignals showsome changes on their position.No IR, Raman, andNMRspectra have been reported for this constant boiling mixture, also there has not been any attempt to nvestigate the unit-structure of this azeotrope. In thiswork the FTIR, FT-Raman, and 1HNMRspectra of pure benzene, puremethanol, and corresponding azeotropewere recorded, mutual influences resulting from azeotrope formation have been analyzed, and spectral changes has been discussed. The unit-structure of cluster has been deduced based on mole ratio, boiling point depression of constituents, and comparison among the spectra obtained by FTIR, FT-Raman, and 1H NMR techniques.

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