Adsorption and Nonlinear Optical Properties of Ascorbic Acid on Silver Clusters: Experimental and DFT Study

The interaction between ascorbic acid (AA) and a silver nanocluster (Ag 3 ) is investigated through a combined experimental and theoretical approach. Density Functional Theory (DFT) calculations at the B3PW91/6‐311++G(d,p) and LanL2DZ levels revealed that adsorption of AA on Ag 3 induces structural reorganization accompanied by charge transfer from Ag 3 to AA. The charge transfer is confirmed by molecular electrostatic potential (MEP), natural population analysis (NPA), Fukui function analysis, and natural bond orbital (NBO) calculations. The reduced band gap of AA–Ag 3 indicates the interaction between AA and Ag 3 . Experimental UV–Vis, Fourier‐transform infrared (FTIR), and Fourier‐transform Raman (FTR) spectra supported the computational findings, revealing changes in electronic and vibrational modes upon adsorption. The first hyperpolarizability (β) of AA–Ag 3 is calculated to be 21 times higher than that of pristine AA. Open‐aperture Z‐scan measurements validated the predicted nonlinear optical (NLO) response, demonstrating the potential of the AA–Ag 3 molecular system for advanced NLO device applications.