Uncovering the dependence of the optical properties of the Au18 nanocluster on the orientation of the oriented external electric field

Abstract

We theoretically demonstrated that the oriented external electric field (OEEF) along the + x direction could precisely and continuously broaden the optical absorption range of an experimentally synthesized Au₁₈ cluster from the visible region to the near infrared (NIR), and significantly enhance its second-order NLO property (∼2090.910 times). By analyzing the excited states and first hyperpolarizability anisotropy, it was observed that the optimal direction for OEEF should align with the axis that exhibits the largest dipole moment. Our work aims to offer a reference for determining the most effective orientation when modulating the optical characteristics of Au NCs through OEEF.