Isotope-Selective Hydrogen-Bond Network Modulations at Plasmonic Gold Nanoparticle Interfaces Probed by Near-Infrared Spectroscopy

Localized surface plasmon resonance (LSPR) in metal nanostructures generates intense, spatially confined electric fields.At the present stage, direct experimental evidence for LSPRinduced perturbations at solid-liquid interfaces remains limited.In this study, we utilize nearinfrared spectroscopy to monitor overtone and combination vibrational modes of HO/DO mixtures, which reflect hydrogen bonding networks, in the presence of colloidal Au nanoparticles under LSPR excitation conditions.Notably, spectral changes were observed exclusively in ACCEPTED MANUSCRIPT isotopically mixed HO/DO solutions (1:1 volume ratio) under LSPR excitation.The power and wavelength-dependent spectral variations-most prominently observed at 6900 cm, corresponding to the first overtone of the O-H stretch-indicate a selective modulations of HOD vibrational modes.Spectral deconvolution reveals that LSPR predominantly perturbs H-D interactions rather than H-H or D-D interactions.These findings highlight an isotope-selective, field-driven reorganization of the interfacial hydrogen bond network, which may contribute to the anomalous kinetic isotope effects observed in plasmon-induced reactions.