Effect of sulfur plus gold sensitization on the delayed formation of latent image specks in a vacuum

Behavior of the delayed formation of latent image specks in a vacuum on sul fur+gold-sensitized emulsions with cubic and octahedral grains was studied. The fraction of developed grains P increased by storing in a vacuum after exposure. In the cubic grain emulsion P exhibited an exponential one-step i ncrease. On the octahedral grain emulsion P indicated a two-step increase. The first step was exponential and the second step was S-shaped. The delaye d formation diminished with the increase of sensitization level and disappe ared completely at the highest level. Latent subimage specks in the sulfurgold-sensitized emulsion were developable by absorbing one photon, but not by adding one silver atom in the delayed formation process. The mechanism o f the two-step increase in developability is also discussed.