Resonance raman spectra of 4 (2-pyridylazo) resorcinol (par) and of its 'CU' (ii) and 'ZN' (ii) chelates: the nature of the low-energy electronic-transition - Oliveira, L F C C; Santos, P S; Ribeiro, Mauro Carlos Costa (Journal of Raman Spectroscopy, 1997)