Effect of UV and X-ray irradiation on optical absorption of PbI2 single crystals

The results of the measurements on the optical absorption of PbI2 single crystals in the range 350-800 nm.; the effect of irradiation by U-V Light in the temperature range 300deg K - 500deg K and by X-rays at room temperature, on absorption characteristics, are reported. These PbI2 crystals exhibit an absorption edge at 520 nm. U-V irradiation increases the absorption in both high and low wavelength region without affecting any chanqe in the absorption edge; but the increase is more prominent in the low wavelength region, possibly due to Mie scattering from small colloidal particles of lead, a product of photolysis due to irradiation. The increase in temperature seems to accelerate the process of colloid formation. The X-rays irradiation brings out similar features as UV irradiation. The change of optical density at a given wavelength increases linearly with X-rays dosage, thus suggesting its possible application in X-rays dosimetry. (author)