Time-Resolved Luminescence Spectra of AgBr at High Density Excitations

Tow new luminescence bands of AgBr have been investigated over a wide range of excitation power. A luminescence band ( M -line) at λ=465 nm is intrinsic to AgBr at high density excitations by a pulsed dye laser, a nitrogen laser and a pico-second Nd 3+ -YAG laser. Dependence of the intensity on the excitation power, the energy position, the line shape, and the response to external magnetic fields of this luminescence band verify that the M -line is due to the partial radiative recombination of “free excitonic molecules” in AgBr. Another band ( Q -band) at λ=478 nm is observed over a wide range of excitations and yields no superlinear dependence on excitation intensity in this range. Multiphonon structure at CW excitation together with sensitive dependence of the intensity on the origin and history of specimens suggest that the Q -band is due to unknown trapped and/ or immobile states in purer but imperfect specimens of AgBr.