Effect of annealing on optical properties of 2-chloro-5-(2,5-dimethoxy-benzylidene)-1,3-diethyl-dihydro-pyrimidine-4,6(1H,5H)-dione thin films

The thermal evaporation technique was used to prepare thin films of CDBP. The films were deposited onto glass and quartz substrates in the ultra-high vacuum at room temperature and annealed at 373 and 388 K for 1 hour. Analysis of X-ray diffraction of powder confirmed that the material has a polycrystalline nature with monoclinic structure and amorphous background with (021) and (012) preferential orientation for as- deposited and annealed films. The absorption coefficient (α) and the refractive index (n) were calculated using spectrophotometric measurements of the transmittance (T) and reflectance (R). Analysis of the spectra of absorption coefficient showed a direct allowed transition and energy gap values increased by annealing. The analysis of refractive index based on single oscillator revealed gives parameters.