Nature Research, Communications Physics, 1(1), 2018
DOI: 10.1038/s42005-018-0069-5
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AbstractThe knowledge advancement in the physics of silicon dioxide has promoted ground-breaking progress, from microelectronics to fibre optics. However, the SiO2 exciton decay mechanism is still mostly unrevealed. Here, we analyse the temperature dependence of interband-excited luminescence and the reflectivity by means of synchrotron radiation on a wide selection of SiO2 materials. This enables us to decouple the band-to-band recombination steps from non-radiative decay pathways that typically mask the relaxation mechanisms. We show that band-to-band excitations decay into two competitive correlated channels leading to green and red luminescence so far ascribed to independent transitions. Here we discuss the assignment to a dual relaxation route involving either ‘free’ or ‘interacting’ non-bridging-oxygen sites. Such an interpretation suggests an explanation for the elusive non-bridging-oxygen centres in quartz. The reflectivity spectra finally demonstrates a general relationship between exciton spectral position and bandwidth in SiO2 and clarifies the role of disorder in exciton localization.