The diffusion of calcium ion into the organic layers studied by a differential photoacoustic system D.M. Hurtado-Castañeda, J. Fernández, E. Gutiérrez, I. Rojas-Molina, J.L. Fernández-Muñoz et M.E. Rodríguez J. Phys. IV France, 125 (2005) 833-836 DOI: 10.1051/jp4:2005125192