Thermal behavior, structure formation and optical characteristics of nanostructured basic fuchsine thin films

Thin films of basic fuchsine, BF, are prepared by thermal evaporation technique. The data of thermal
gravimetric analysis, TGA, showed that BF has a thermal stability up to the temperature of 265 C. The
structural characteristics of BF thin films are investigated by using X-ray diffraction, and atomic force
microscope techniques. BF is polycrystalline in powder form; it becomes nanocrystallites in thin film
condition. Annealing temperatures decreased crystallites size and influenced optical constants of BF
films. Optical constants of BF films were estimated by using spectrophotometer measurements of
transmittance and reflectance in the spectral range from 190 to 2500 nm. The dependence of absorption
coefficient on the photon energy and annealing temperatures was determined and the analysis of the
results showed that the optical transition in BF films is indirect allowed one. The onset and fundamental
energy gap of BF thin films are 1.91 and 3.72 eV, respectively and they decrease by annealing temperatures.
The optical dielectric constants and dispersion parameters of BF thin film are calculated and
showed remarkable dependence on photon energy and annealing temperatures