EFFECT OF ACCUMULATED RADIATION-DOSE ON PULSE-RADIOLYSIS CONDUCTIVITY TRANSIENTS IN A MESOMORPHIC OCTA-N-ALKOXY-SUBSTITUTED PHTHALOCYANINE

The transient conductivity induced by nanosecond pulse radiolysis of octa-n-nonyloxyphthalocyanine has been studied as a function of accumulated radiation dose, SIGMAD, from 10 Gy to 250 kGy. The end-of-pulse conductivity, DELTAsigma(eop)/D, is unaffected by SIGMAD up to 150 kGy. Above this, DELTAsigma(eop)/D begins to decrease and at 250 kGy is 65% of the low-dose value. An increase in the rate of decay of the transient conductivity in the solid state can be observed at values of SIGMAD as low as 10 kGy. On heating to the liquid crystalline phase and resolidifying, the conductivity decay returns to that found for the virgin material. However, DELTAsigma(eop)/D remains low. The solid to mesophase transition temperature, as monitored by differential scanning calorimetry, was found to be a few degrees lower after a total accumulated dose of 260 kGy.