Vibrational spectra of α-naphthol,β-naphthol andβ-naphthol-OD have been recorded in the solid and solution phases. A number of bands, common to all the three compounds, have been correlated with earlier naphthalene assignments and an attempt has been made to identify certain frequencies with vibrational modes that are centred in the substituentsOH andOD. TheC_s symmetry is assumed for each molecule.

The longest wavelengthπ* ←π electronic band system of ortho-hydroxybenzonitrile vapour through the absorption technique has been reported for the first time. Assuming a planar molecular geometry in both the electronic states, the molecule is classified into aC_s point group, and the present spectrum is attributed to¹A′ ←¹A′ type corresponding to electric dipole forbidden transition¹B_2u ←¹A_1g (260 nm band system) of benzene. The most intense band at 33914 cm⁻¹ has been assigned as the 0, 0 band, and the other vibronic bands have been interpreted in terms of the excited state and a few ground state fundamentals.

The optical absorption spectra of EuCl₃ in aqueous and acidic solutions were measured in the visible anduv regions of the spectrum. The concentration as well as the temperature of the solutions were varied to establish an accurate free-ion energy level scheme of Eu³⁺. The energy levels were assigned on the basis of a correlation between the calculated and the experimentally observed transition energies and associated band intensities.