The mechanism of action behind the photochemical properties of silver halides in photographic materials involves the absorption of light, the formation of a latent image, and the development process to form a visible image. Silver halides, such as silver bromide AgBr and silver chloride AgCl , are light-sensitive compounds that are used as the active components in photographic materials, such as photographic film and paper.1. Absorption of light: When silver halides are exposed to light, they absorb photons, which causes the excitation of electrons from the valence band to the conduction band. This process creates electron-hole pairs, where the electron is a free electron in the conduction band, and the hole is a positive charge left behind in the valence band.2. Formation of a latent image: The excited electrons can be trapped by defects or impurities in the crystal lattice of the silver halide, such as silver ions Ag+ or other dopants. This trapping process leads to the reduction of silver ions to form metallic silver Ag atoms. The accumulation of these silver atoms forms a latent image, which is an invisible image that represents the distribution of light intensity in the original scene.3. Development process: To make the latent image visible, the photographic material is treated with a developing agent, which is typically a reducing agent that can selectively reduce the exposed silver halide crystals to metallic silver. The unexposed silver halide crystals are not affected by the developer and remain unchanged. The metallic silver forms a visible image, which is a negative image of the original scene, with dark areas representing the bright regions and vice versa.4. Fixing and washing: After development, the photographic material is treated with a fixing agent, which removes the unexposed and undeveloped silver halide crystals, leaving behind only the metallic silver image. The material is then washed to remove any residual chemicals, and the image is allowed to dry.In summary, the photochemical properties of silver halides in photographic materials involve the absorption of light, the formation of a latent image through the trapping of excited electrons and the reduction of silver ions, and the development process to selectively reduce the exposed silver halide crystals to form a visible image. This mechanism allows the capture and preservation of images based on the distribution of light in a scene.