Optical absorption of sodium copper chlorophyllin thin films in UV-vis-NIR region.

The optical absorption studies of sodium copper chlorophyllin thin films (SCC), prepared by spray pyrolysis, in the UV-vis-NIR region was reported for the first time. Several new discrete transitions are observed in the UV-vis region of the spectra in addition to a strong continuum component in the IR region. The spectra of the infrared absorption allow characterization of vibration modes for the powder and thin films of SCC. The absorption spectrum recorded in the UV-vis region showed different absorption bands, namely the Soret (B) in the region 340-450 nm and Q-band in the region 600-700 nm and other band labeled N in the 240-320 region. Some important spectral parameters namely optical absorption coefficient (alpha), molar extinction coefficient (epsilon(molar)), oscillator strength (f), electric dipole strength (q(2)) and absorption half bandwidth (Deltalambda) of the principle optical transitions were evaluated. The analysis of the absorption coefficient in the absorption region revealed direct transitions and the energy gap was estimated as 1.63 eV. Discussion of the obtained results and their comparison with the previous published data are also given.