Dyes in infrared photography

摘要

The development of infrared sensitising dyes are discussed with emphasis on their structural types. All photographic films and papers are multicomponent systems containing silver halides, gelatin, dispersing agents, hardening agents, stabilising agents, chemical sensitizers, imaging dyes, couplers and others. Among all these photosensitive elements of photographic materials are the silver halide microcrystals. The absorption of a photon by the microcrystal releases a free electron, which is immediately trapped by a sensitivity centre. Subsequently, an interstitial silver ion reaches and reacts with the trapped electron to form a silver atom. Such electronic and ionic processes are repeated at the same center leading to the formation of a latent image comprising of several silver atoms.