OICC Press International Nano Letters 2228-5326 3 1 (December 2013) 2013 03 28 Spectroscopy-based study on the interaction between gold nanoparticle and poly(vinylpyrrolidone) molecules in a non-hydrocolloid 10.1186/2228-5326-3-17 EN Manoranjan Behera Chemistry Department, Silicon Institute of Technology, Bhubaneswar, 751 024, IN Materials Science Centre, Indian Institute of Technology, Kharagpur, 721 302, IN Shanker Ram Materials Science Centre, Indian Institute of Technology, Kharagpur, 721 302, IN Journal Article 2013 03 28 Abstract The study of the interaction between poly(vinylpyrrolidone) (PVP) and gold (Au) nanoparticles (NPs) in a colloid is of special interest for possible applications in the field of catalysis, biosensing, and biomedicine. A strong optical absorption arising from Au NPs at 532 nm in Au-PVP colloids is ascribed to surface plasmon resonance. The X-ray photoelectron spectroscopic results confirm reduction of the Au 3+ ion to Au 0 . A noticeable decrease in the binding energies of the Au4 f doublet peak of the Au NP with PVP as compared to the bulk Au atom implies interfacial interaction between the Au NP and PVP molecules. A marked enhancement in vibrational band intensities of C-H (2,961, 2,936, and 2,872 cm −1 ) stretching, C-N (1,463 cm −1 ) stretching, and CH 2 (1,381 cm −1 ) bending vibrations in the pyrrolidone ring of PVP molecules reveals a charge-transfer-type interaction between the PVP molecules and surface of the Au NP. A significant decay of the emission band intensity (approximately 85%) in the π ← π* band of the PVP molecules at approximately 392 nm in the presence of Au NPs suggests non-bonding ( n ) electron transfer from the O atom of the pyrrolidone ring of PVP molecules to the electron-deficient Au NP. A negative zeta potential of (−) 15.2 mV reveals accumulation of n -electrons of the O atom of the carbonyl group of PVP molecules on the surface of the Au NP. Transmission electron microscopic images of PVP-capped Au NPs corroborate the spectroscopic results.