PHOTOGRAPHIC PRODUCTS AND PROCESSES

摘要

A novel class of bridged indicator dyes is disclosed which possess absorption in the infrared region of the electromagnetic spectrum. These bridged indicator dyes are useful as light-absorbing, pH-sensitive optical filter agents in diffusion transfer photograpic processes adapted to be performed in the presence of ambient light and to diffusion transfer products useful in such processes. These indicator dyes will also find utility in titrations and other analytical techniques and products where pH-sensitive indicator dyes are employed and absorption of infrared is useful.