Lanthanide Complexes for Second Order Nonlinear Optics: Evidence for the Direct Contribution of f Electrons to the Quadratic Hyperpolarizability,
Nicolas Tancrez, Christophe Feuvrie, Isabelle Ledoux, Joseph Zyss, Loïc Toupet, Hubert Le Bozec, and Olivier Maury,J. Am. Chem. Soc. 127(39), pp. 13474-13475 (2005).