Scuppa Stefano, Orian Laura, Dini Danilo, Santi Saverio, Meneghetti Moreno
Department of Chemical Sciences, University of Padova, Via Marzolo 1, I-35131 Padova, Italy.
J Phys Chem A. 2009 Aug 20;113(33):9286-94. doi: 10.1021/jp9047192.
We report on the first observation of reverse saturable absorption by ferrocene (Fc) in toluene using nanosecond pulses at 532 nm. Pump and probe experiments in the visible spectral region show the existence of an excited triplet state with an intersystem crossing quantum yield S1 --> T1 of 0.085 and a molar extinction coefficient epsilon(Fc)(T) of 5650 L mol(-1) cm(-1) at 700 nm. The full understanding of the nonlinear optical behavior of Fc cannot be obtained, however, with a model that includes only the one-photon absorption from T1, but it is mandatory to consider also a simultaneous two-photon absorption from an excited singlet state of Fc (two-photon absorption cross section: 2.4 x 10(-41) cm4 s ph(-1) mol(-1)). The optical spectrum of the ground and triplet state of Fc are calculated within a TD-DFT approach considering several functionals (PBE, BLYP, LDA, OPBE) for the optimization of molecular geometry.
我们报道了首次利用532nm的纳秒脉冲观察到二茂铁（Fc）在甲苯中的反饱和吸收现象。可见光谱区域的泵浦-探测实验表明，存在一个激发三重态，其系间窜越量子产率S1→T1为0.085，在700nm处的摩尔消光系数ε(Fc)(T)为5650 L mol⁻¹ cm⁻¹。然而，仅包含从T1的单光子吸收的模型无法完全理解Fc的非线性光学行为，还必须考虑同时从Fc的激发单重态进行的双光子吸收（双光子吸收截面：2.4×10⁻⁴¹ cm⁴ s ph⁻¹ mol⁻¹）。在TD-DFT方法中，考虑了几种用于优化分子几何结构的泛函（PBE、BLYP、LDA、OPBE），计算了Fc基态和三重态的光谱。
