Enhancement of Radiation Sensitivity on Silver-Salt Photographic Materials by Post-Exposure Latensification with Red Light at Low Temperature

Abstract

During the radiation exposures to silver-salt photographic materials, small and undevelopable latent sub-image specks (LSIS) are often formed at several sites, and so the dispersion of photolytic silver clusters reduces the sensitivity. We examined the effect of post-exposure latensification with red light at low temperature, in which LSIS was reconstituted to increase the sensitivity. The grain density (GD) of the tracks increased when the photographic film irradiated with heavy-ion beam was exposed with red light at -30°C. This effect is thought to be similar to the Herschel effect. When LSIS absorbs red light and so an electron in silver atom is excited to conduction band of silver halide, another LSIS captures the electron to grow into a developable latent image speck. The exposure at low temperature inhibits the red-light sensitivity of chemical-sensitization centers. The large effect was obtained in cases that the GD was small, such as photographic plates were exposed with ion beam of less energy-loss or developed with weak developer.