title: Probing the interaction of poly(vinylpyrrolidone) with platinum nanocrystals by UV-Raman and FTIR.
abstract: The vibrational spectra of platinum nanoparticles (2.4-9 nm) capped with poly(N-vinylpyrrolidone) (PVP) were investigated by deep UV-Raman and FTIR spectroscopy and compared with those of pure PVP. Raman spectra of PVP/Pt show selective enhancement of C=O, C-N, and CH2 vibrational modes attributed to the pyrrolidone ring. Selective enhancement of ring vibrations is attributed both to the resonance Raman effect and SERS chemical enhancement. A red shift of the PVP carbonyl frequency on the order of 60 cm-1 indicates the formation of strong >C=O-Pt bonds. It is concluded that PVP adheres to the nanoparticles through a charge-transfer interaction between the pyrrolidone rings and surface Pt atoms. Heating the Pt nanoparticles under reducing conditions initiates the decomposition of the capping agent, PVP, at a temperature 100 degrees C below that of pure PVP. Under oxidizing conditions, both PVP/Pt and PVP degrade to form amorphous carbon.
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Borodko
authors.forename: Susan E
authors.initials: SE
authors.lastname: Habas
authors.forename: Matthias
authors.initials: M
authors.lastname: Koebel
authors.forename: Peidong
authors.initials: P
authors.lastname: Yang
authors.forename: Heinz
authors.initials: H
authors.lastname: Frei
authors.forename: Gabor A
authors.initials: GA
authors.lastname: Somorjai
mesh_terms: D002244:Carbon / Q000737:chemistry; D005030:Ethylenes / Q000737:chemistry; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010984:Platinum / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry*; D011760:Pyrrolidinones / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods; D013696:Temperature; D000267:Tissue Adhesions
chemical_list: D005030:Ethylenes; D011145:Polyvinyls; D011760:Pyrrolidinones; D010984:Platinum; D002244:Carbon; C036216:ethylene; D009584:Nitrogen; D010100:Oxygen