Gamma irradiation effect on mixed dye film; its possible use as a radiation dosimeter

The polymer films under investigation include poly (vinyl alcohol) in a combination with mixture of two dyes, namely, 2,6-dichlorophenol indophenol sodium salt (DCP), and tetrabromophenol blue (TBPB) as pH indicator in presence of various chloral hydrate concentrations. These films undergo color change from the blue to the yellow color passing through green as an intermediate state. The decoloration of DCP started first in the beginning of reaction, followed by the transformation of TBPB to its acidic form as a result of the delivery of HCl from the radiolysis of chloral hydrate. The dosimetric parameters, eg; dose response, effect of relative humidity on response as well as before and after irradiation stability of these films were inspected. The energy band gap value of the prepared films decreased from 1.83 to 1.75 against absorbed dose. These films can be used as dosimeters for food irradiation applications where the useful dose range is recorded from 1 to 15 kGy. (author)