Synthesis and third-order nonlinear optical properties of PEGylated platinum nanoparticles

• PEGylated platinum nanoparticles were synthesized via wet chemical method . • Nonlinear optical characteristics of PEGylated Pt NPs are discussed. • 3rd Order NLO behaviour is examined through the Z-scan methodology. • NLA coefficient for PEGylated Pt NPs is in the range of 10 −4 cm/W. • NLR index is in the range of 10 −10 cm 2 /W. PEGylated platinum nanoparticles , which are capped with polyethylene glycol-400, are synthesized through the chemical reduction technique. The sample was comprehensively characterised through UV–visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD pattern for the sample revealed a face-centered cubic crystalline phase of platinum, with a lattice constant of 3.939 Å. The average particle size, obtained from high-resolution electron microscopy analysis, is 3.73 nm. The third order NLO features were explored through the Z-scan technique, employing a continuous wave regime. The observed phenomena of nonlinear absorption (NLA) and nonlinear refraction (NLR) are attributed to reverse saturable absorption and thermal lens models. NLR index was measured to be in the range of 5.72 × 10 −10 cm 2 /W, while NLA coefficient was found to be in the range of 1.86 × 10 −5 cm/W, highlighting the potential of PEGylated Pt NPs for NLO applications.