Radiochromic properties of organic films based on a diarylethene molecule

Poly(methyl methacrylate) (PMMA) films containing photochromic molecules, 2,3-bis(2,4,5-trimethyl-3-thienyl)maleimide (BTTM), were fabricated and assessed for their radiochromic behavior. The rate of the absorbance with dose for the PMMA films was directly proportional to BTTM concentration. The peak wavelength of the absorption band was slightly different from that upon UV irradiation. In addition, the radiation-induced state was not stable at room temperature in contrast to the case of UV irradiation. With the addition of a fluorescent organic compound, 2-(4-tert-Butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (b-PBD), an increase in the rate of absorbance was enhanced by a factor of two, because BTTM was additionally changed upon absorption of scintillation from b-PBD. The radiation-induced state at room temperature was stable at room temperature with the addition of b-PBD.