Optical absorption of tetraphenylporphyrin thin films in UV-vis-NIR region

The optical absorption of thermally-evaporated tetraphenylporphyrin (TPP), in the UV-vis-NIR region has been studied. The absorption spectra recorded in the UV-vis region for the as-deposited and annealed films showed different absorption bands, namely the Soret, B, at region 360-490 nm, Q-band region consist of four bands in the region 500-720 nm and two other bands labeled N and M in UV region. The Soret band always shows splitting in all the TPP thin films and the effect of annealing on the intensities of these components have been observed. The spectra of the infrared absorption allow characterization of vibrational modes for the powder, as deposited and annealed thin films. Some of the optical absorption parameters, namely molar extinction coefficient (epsilon), half band width (Deltalambda), electronic dipole strength (q2), and oscillator strength (f), of the principal optical transitions have also been evaluated.