What is the primary chemical process underlying the physical developer technique?

The primary chemical process underlying the physical developer technique involves the formation of silver and a ferrous/ferric redox couple. This technique is particularly important in the context of developing latent fingerprints on porous surfaces.

In this process, ferrous ions are oxidized to ferric ions, which allows for the deposition of silver onto the fingerprint residues. The silver ions adhere to the organic material present in the latent print, which enhances the visibility of the print and allows for further examination and analysis. This redox reaction is crucial because the presence of moisture can aid the oxidation and thus the overall effectiveness of the physical developer, making it a highly reliable method for latent print development on surfaces that may have absorbed water or other contaminants.

The other options do not accurately capture the primary mechanism involved in this technique. While oxidation of iron compounds does occur, it is part of the broader redox reaction involving silver. Electrostatic adhesion and non-specific chemical binding would not adequately describe the chemical interactions involved in the physical developer technique, as these processes do not specifically involve the reactions that enhance the visibility of latent prints in the context described.