Structural and optical properties of thermally evaporated 2-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-ylimino)-2-(4-nitrophenyl)acetonitrile thin films

The structural and optical properties of as-deposited and γ-rays irradiated 2-(2,3-dihydro-1,5dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-ylimino)-2-(4-nitrophenyl)acetonitrile (DOPNA) thin films have been reported. The structural properties of as-deposited and γ-rays irradiated DOPNA thin films are characterized by Fourier transformation infrared, X-ray diffraction and transmission electron microscope techniques. The transmittance, T(λ), and reflectance, R(λ), are measured at the normal incidence of light by a double beam spectrophotometer in the wavelength range 200–2200 nm. The refractive and absorption indices have been calculated. The dispersion parameters such as dispersion energy, oscillator energy and dielectric constant at high frequency are evaluated. The data of the absorption coefficient are analyzed in order to determine the type of inter-band electronic transitions and the optical band gap of the films. Other optical absorption parameters, namely, the extinction molar coefficient, oscillator strength and the electric dipole strength, are also calculated.