Optically-detected magnetic resonance of molecular color centers CO3- and NO3 in gamma-irradiated beryl

In this paper we identify, with optically-detected magnetic resonance via the magnetic circular dichroism of the absorption, the NO3 and CO3– molecular radicals trapped in the structural channels of gamma-irradiated beryl. We confirm that, along with the CO3–, the NO3 is also responsible for the blue color by introducing several absorption peaks between 14500 cm–1 and 18000 cm–1 (720 nm down to 540 nm). Their individual contributions to the overall many-peak optical spectra have been established and most of the transitions could be explained in terms of a combination of crystal-field and spin-orbit split 2A2′ 2E′ transition plus vibronic replicas. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)