Optical Gas Sensing of Ammonia and Amines Based on Protonated Porphyrin/TiO2 Composite Thin Films. - Pedro Castillero; Javier Roales; Tânia Lopes-Costa; Juan R. Sánchez-Valencia; Angel Barranco; Agustín R. González-Elipe; José M. Pedrosa (Sensors, 2017)