The Relevance of the Octupolar Contribution to the Quadratic Hyperpolarizability of Dipolar Neutral Ir(III), Pt(II) and Ru(II) Complexes. - Dragonetti, Claudia; Righetto, Stefania; Roberto, Dominique; Ugo, Renato; Valore, Adriana; Ledoux-Rak, Isabelle (Nonlinear Optics, Quantum Optics: Concepts in Modern Optics, 2011)