Comparison of Palladium Nuclei and Silver Nuclei in Photoactivation Type Physical Development

Abstract

A photoactivation type physical developer is proposed which can stand storing for long period. Some basic characteristics; the stability of developer, the deposition efficiency of image silver and the effects of anion species and nucleus metal on the developing rate, were studied. The developer consisted of a meatanol-water solution of silver salt (0.5 mol/l) and p-benzo quinone (0.47 mol/l). The photographic image were formed on photosensitive films of 2- isopropoxy-1, 4-naphthoquinone dissolved in cellulose acetate. The image forming steps wer (1) the imagewise exposure (365 nm, 7.5x1015 photons/cm2. s, 10 s), (2) the first development o nucleus formation (immersion of the exposed film into Ag+ or Pd2+ methanol-water solution 10 s) and (3) the second development or image silver deposition under UV irradiation of th developer. The developing time could be made much shorter when palladium nuclei rather than silve nuclei were used. The overall photographic speed was 4 times faster with palladium nuclei The anion of the silver salt affected the silver depesition rate on the silver nuclei. The deve lopment with AgBF4 was found not to exhibit any significant induction period while th, development with AgNO3 showed an induction period of several minutes. The developer after storage for two days did not show any deterioration in the developing power. From the, practical point of view the photoactivation type physical developer proposed could be store almost for a week. The ratio of the amount of silver utilized for image formation to the whole silver consumption was 1-3%. The resolution power of image varied over 80-241 line pairs/mm, depending on the anion species in the developer and also on the nucleus metal. Photo-activation Type Physical Developer. II.