Influence of proton irradiation on the photochromism

The objectives of this study are to extend our knowledge on the radiochromic reaction mechanism of photochromic compounds and to accumulate the basic data needed for the development of a low-cost radiochromic film dosimeter. The characteristics of the radiochromic reaction of SPO, were studied by UV-Vis and chromatographic methods. The results of the radiochromic reaction was compared with the effects of UV light on photochromic reaction of SPO. The basic data for selecting the proper materials and conditions were also obtained. Upon the proton irradiation, SPO decomposes into two chemicals (1 and 2). 1 is contains indoline group and 2 contains phenanthrene group. 2 absorbs at 480 nm and has acidic character. By the UV irradiation, SPO also decomposes to give the same products as the radiochromic reaction. Depending on the solvent trans-PMC·HCl or cis-PMC·HCl complex was produced upon the addition of HCl on SPO solution and two complexes seemed to be unstable in a given condition. It seems that 1x10-3 M SPO/ethanol solution is very suitable system for the radiochromic dosimeter in the fluence range of 8x1011 ∼ 2x1013 ions/cm2. SPO/acetonitrile and SPO/PS system were also good candidates for the dosimeter application.