Structural and optical studies on ortho-hydroxy acetophenone azine thin films

The bulk material and deposited thin films of ortho-hydroxy acetophenone azine (o-HAcPhAz) were identified by X-ray diffraction (XRD) to be single phase polycrystalline of the monoclinic structure. The unit cell lattice constants were determined to be a = 1 578 nm, b = 1 394 nm and c = 0 64 nm, as well as its plane angles as alpha = 90degrees, beta = 123 8 and gamma = 90degrees. FTIR spectra of the bulk and thin films of the compound under investigation were assigned in the wave number range 4000-500 cm(-1). It was revealed that they were similar to each other. The optical constants (the refractive index, n, and the extinction coefficient, k) of the compound thin films were determined from the measured transmittance, T, and reflectance, R, at normal incidence of light in the spectral range 200-2100 nm. The plot of the absorption coefficient (alpha) versus hnu, gave three intense bands and a shoulder which were designated as A (232.3 nm), B (299.5 nm) and C (440.6 nm, 404.8 nm, sh). The observed A and B bands were attributed to pi pi* transitions, while the C-bands were attributed to pi* <-- σ (n). The optical high frequency dielectric constant (ε(1), ε(2)) as well as the real and imaginary parts of the optical conductivity (σ(1), σ(2)) were determined. The plots of both ε(1),ε(2), σ(1) and σ(2) versus hν reveal the same obtained optical transitions. Also, the relationships between both of surface, volume and surface/volume energy losses against hν gave the same optical transtions. (C) 2002 Kluwer Academic Publishers.