Hybrid organic-inorganic photochromic xerogels studied by solid state nuclear magnetic resonance and electronic paramagnetic resonance - Oliveira Junior, Marcos de; Schneider, José Fabian; Rodrigues Filho, Ubirajara Pereira; Magon, Claudio José (Workshop on Sol-Gel Chemistry and Processes for Ceramic, Composites and Inorganic-Organic Hybrid Materials, 2013)