Radiochromic properties of alfa-terthiophene-cellulose triacetate films

An a-terthiophene/cellulose triacetate ®lm system exposed to g-rays and electron beam shows two new bands in the visible region of the spectrum. The absorbance at 490 nm is almost stable for a long time and responds linearly to the dose applied up to 400 kGy. A second band developed at 700 nm depends on dose rate and may indicate a chain-growth. The main species responsible for the color change and EPR signal is likely to be an enlarged oligomer radical cation stabilized by a semiquinoid structure.