Journal of Natural Sciences

Structural , and Photochromic Properties of Thermally Evaporated E-3-(Adamantan -2-Ylidene)-4-[1 - (2,5-Dimethy-3furyl) Ethyldene] Dihydro-2,5-Furandione Thin Films
M. M. El- Nahass, A. M. A. El-Barry

Abstract
Thin Films of E-3-(Adamantan -2-Ylidene)-4-[1 - (2,5-dimethy-3furyl) ethyldene] dihydro-2,5- Furandione compound were prepared by conventional thermal evaporation technique. X-ray diffraction patterns indicated that the compound in the powder form has a polycrystalline nature with momoclinic structure . The Miller indices for the powder were calculated for the first time using Check,s cell program . SEM indicated the short range order of the films. FTIR indicated the consistent of both the powder and the as-deposited thin films. The films were irradiated with UV light (360 nm) for different times from 1 to 11 min. The color of the films converted to saturated rose color after an exposure time ≅ 6 min . The photobleaching time was found to be 13.5 min under the effect of Vis light, using a white light. This behaviour deduced the photochromic effect of the compound which has been explained according to the presence of the open cycle E-isomer which converted to the closed C-isomer under the effect of the UV-light. The refractive index, n, and the absorption index, k, and the the parameters of molar extinction coefficient (εmolar) were evaluated for both as deposited and the colored films. The concentration of the coloring centers through the thin films were found to be ~ 1.18 x10 10 /cm3 . The studying of the dispersion spectra indicated abnormal behaviour companied with plasma frequency. Finally; The analysis of the absorption coefficient revealed the present of direct optical gap with 3.17 ±0.006 eV for the deposited films ,which decreased to 2.48 ±0.003 eV for the colored films .

Full Text: PDF     DOI: 10.15640/jns.v5n1a2