Photodynamics of a Molecular Water-Soluble Nanocluster Identified as Au₁₃₀(<i>p</i>MBA)₅₀

Photodynamics of a highly monodisperse sample of a water-soluble gold nanocluster tentatively identified as Au₁₃₀(<i>p</i>MBA)₅₀ (<i>p</i>MBA = <i>p</i>-mercaptobenzoic acid) was studied by mid-IR transient absorption spectroscopy with visible excitation. The observed long-lived excited states (>1 ns) indicate a molecular behavior of the cluster. By combining the transient absorption data with DFT calculation results the observed relaxation dynamics could be fully explained by identifying several relaxation processes involving singlet and triplet manifolds. The results indicate that the cluster may have interesting transient magnetic properties due to a long-lived triplet population