In recent years electron transfer rates have been measured from excited dye
molecules of both monomeric and J-aggregate form into silver halide crysta
ls over a nide range of temperatures with picosecond time resolution. From
these new experimental results, one obtains definite information about the
energetics, electronic coupling strengths, and dynamic parameters of the re
action. These data can serve as the first basis for a detailed comparison a
nd test of notions that have been advanced in the past to describe the rele
vant energetics and dynamics of the primary electron injection process into
silver halide grains. The comparison will be made in particular with the m
odels that have been widely used in the past by the photographic community,
but also with the somewhat different concepts that have been developed for
other closely related physical systems.