ESR and Optical Absorption of Ag in a N2 Matrix

Ag atoms isolated in N₂ matrices were studied by simultaneous observation of optical absorption and electron spin resonance (ESR). In matrices with low Ag/N₂ ratios two ESR signals were observed, both of which could be correlated to the well known absorption triplet corresponding to the 5s ²S → 5p ²P resonance transition. One of the two ESR signals disappeared irreversably upon annealing up to 20 K. The stable species is attributed to Ag atoms in a nanocrystalline environment whereas the unstable species corresponds to atoms in the non-crystalline regions between the crystallites. In higher doped matrices a new Ag spectrum showed up, both in the optical absorption and in the ESR. It is assigned to Ag atoms with near-by complexes, possibly Ag clusters.