Impact of γ-rays Irradiation on Hybrid TiO-SiO Sol-Gel Films Doped with RHODAMINE 6G.

In the present paper, we investigate how the optical and structural properties, in particular the observed photoluminescence (PL) of photocurable and organic-inorganic TiO-SiO sol-gel films doped with Rhodamine 6G (R6G) are affected by γ-rays. For this, four luminescent films, firstly polymerized with UV photons (365 nm), were submitted to different accumulated doses of 50 kGy, 200 kGy, 500 kGy and 1 MGy while one sample was kept as a reference and unirradiated. The PL, recorded under excitations at 365 nm, 442 nm and 488 nm clearly evidences that a strong signal peaking at 564 nm is still largely present in the γ-irradiated samples. In addition, M-lines and Fourier-transform infrared (FTIR) spectroscopies are used to quantify the radiation induced refractive index variation and the chemical changes, respectively. Results show that a refractive index decrease of 7 × 10 at 633 nm is achieved at a 1 MGy accumulated dose while a photo-induced polymerization occurs, related to the consumption of CH=C, Si-OH and Si-O-CH groups to form Ti-O and Si-O bonds. All these results confirm that the host matrix (TiO-SiO) and R6G fluorophores successfully withstand the hard γ-ray exposure, opening the way to the use of this material for sensing applications in radiation-rich environments.