PHOTOGRAPHIC GELATIN LAYER MICROSTRUCTURES REVEALED BY IMAGING SECONDARY-ION MASS-SPECTROMETRY

We have used the imaging secondary ion mass spectrometry (SIMS) technique to study fundamental aspects of the chemistry and morphology of photographic gelatin. Studies of thin, dilute gelatin layers spread on flat supports provide information about the fibril macrostructure of the gelatin and about the interaction of the gelatin with embedded silver halide crystals. The structure of the dried thin layers is a function of many parameters, including the pH of the gelatin solution before dispersal. Also, gelatin fibrillar structures form and are oriented by the surfaces of tabular and cubic AgBrX crystals. The dimensions of these fibrils associated with the crystals are many times larger than the expected dimension of an isolated gelatin triple helix. Cross sections through a commercial film are also examined with SIMS at high spatial resolution (better than 100 nm). The results are discussed in the context of current theories about the structure of gelatin and how this structure affects the photographic properties of silver halide films. We compare and review the findings from other instrumental methods.