Effect of Au and Au@Ag core-shell nanoparticles on the SERS of bridging organic molecules.
Gold nanoparticles (AuNPs) with about 6 nm size were produced and stabilized with mercaptopropionic acid (MPA) film to produce a monolayer protected cluster (MPC) of AuS(CH(2))(2)COOH. 4-Aminothiophenol (ATP) molecules were introduced to the activated carboxylic acid ends of the film surrounding the AuNPs to produce AuS(CH(2))(2)CONHPhSH MPC. These modified AuNPs were again self-assembled with Au@Ag core-shell bimetallic nanoparticles via the -SH groups to produce an organic bridge between Au and Au@Ag metallic nanoparticles. An unusually strong enhancement of the Raman signals was observed and assigned to the plasmon coupling between the AuNPs and Au@Ag NPs bridged assembly. Formation of AuS(CH(2))(2)COOH and AuS(CH(2))(2)CONHPhSH clusters and AuS(CH(2))(2)CONHPhS(Au@Ag) assembly is confirmed by UV-Vis, reflection-absorption IR spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS), as well as by TEM analysis. The SERS activity of the AuNPs and Au@Ag NPs was tested using the HS(CH(2))(2)CONHPhSH molecule as a probe to compare the effectiveness of monometallic and bimetallic systems. SERS spectra show that Au@Ag bimetallic nanoparticles are very effective SERS-active substrates.
Güzel
Remziye
R
Dicle University, Faculty of Arts and Sciences, Dept. of Chemistry, Diyarbakir, Turkey.
Ustündağ
Zafer
Z
Ekşi
Haslet
H
Keskin
Selda
S
Taner
Bilge
B
Durgun
Zeynep Gülşah
ZG
Turan
Aybüke A Isbir
AA
Solak
Ali Osman
AO
D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D015394:Molecular Structure; D050607:Organogold Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
D050607:Organogold Compounds; D012834:Silver; D006046:Gold