Inhomogeneous Broadening: Symmetry of Centers and Disorder in Solid Solutions and NanocrystalsS.P. Feofilov, A.A. Kaplyanskii, A.B. Kulinkin, R.I. Zakharchenya, K. Ovanesyan, A. Petrosyan and C. DujardinEPJ Web of Conferences, 103 (2015) 01003DOI: https://doi.org/10.1051/epjconf/201510301003