Work Function, Electrostatic Force Microscopy, Tunable Photoluminescence of Gold Nanoparticles, and Plasmonic Interaction of Gold Nanoparticles/Rhodamine 6G Nanocomposite

The work function and tunable photoluminescence of gold nanoparticles (AuNPs) and their interaction with Rhodamine 6G (R6G) molecules were characterized using scanning probe microscopy (SPM) and spectroscopy techniques. Atomic Force Microscopy (AFM) and Kelvin Probe Force Microscopy (KPFM) were employed to analyze the surface roughness and work function of AuNPs ranging in size from 3 to 21 nm. According to measurements with Kelvin Probe Force Microscopy (KPFM), the work functions for AuNPs are approximately 5.17 eV, 5.14 eV, and 5.13 eV for the range of sizes of nanoparticles. It was observed that larger AuNPs have increased surface roughness and consequently decreased work function. Additionally, phase imaging and Electrostatic Force Microscopy (EFM) were utilized to further investigate the AuNPs/R6G composites, revealing their surface nanoscale distribution and their electrical properties. In addition, the tunable photoluminescence of AuNPs based on excitation wavelength was studied, showing that as the excitation wavelength increases, the photoluminescence shifts to higher emission wavelengths and the peak intensity increases. Furthermore, UV–visible absorption and photoluminescence spectroscopy were employed to investigate the optical properties of AuNPs added to Rhodamine 6G molecules, revealing an enhancement in absorption and a reduction in photoluminescence.