Structural and optical characterizations of Ni (II) tetraphenyl porphyrin thin filmsM.M. El-Nahass, H.M. Abd El-Khalek and A.M. NawarEur. Phys. J. Appl. Phys., 57 3 (2012) 30201DOI: https://doi.org/10.1051/epjap/2012110280