Optical spectroscopy of Eu3+ ion as a tool for the study of dehydration process in silica gels A. PIAZZA, A. BOUAJAJ, M. FERRARI, M. MONTAGNA, R. CAMPOSTRINI et G. CARTURAN J. Phys. IV France, 04 C4 (1994) C4-569-C4-572 DOI: 10.1051/jp4:19944137