The Fourier-transform infrared (FT-IR) technique has been applied to identify the polymorphs of phthalocyanine molecules. The infrared absorption (IR) spectra were recorded in the spectral range 400-1000 cm(-1). A comparison of absorption spectra of powder, as-deposited and annealed films is presented. The powder absorption spectrum was identified as rich of beta-NiPc, where the thermally deposited films at room temperature were identified as the rich of alpha-NiPc. Moreover, the main spectral peaks of the films, annealed at 573 K, were defined as rich of beta-form. The absorption measurements recorded in the UV-vis region showed two well-defined absorption bands of phthalocyanine molecule, namely the Soret band (B) and the Q-band. The Q-band showed its characteristic splitting (Davydov splitting), and Delta Q was obtained as 0.21 eV. Some of the important optical absorption parameters such as the molar extinction coefficient, the oscillator strength, and the electric dipole strength have been evaluated. (c) 2005 Elsevier B.V. All rights reserved.