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Single molecule surface‐enhanced resonance Raman scattering on colloidal silver and Langmuir–Blodgett monolayers coated with silver overlayers
Author(s) -
Lemma Tibebe,
Aroca Ricardo F.
Publication year - 2002
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.833
Subject(s) - monolayer , langmuir–blodgett film , raman scattering , molecule , chemistry , analytical chemistry (journal) , raman spectroscopy , overlayer , perylene , silver nanoparticle , adsorption , colloid , photochemistry , materials science , nanotechnology , nanoparticle , organic chemistry , optics , biochemistry , physics
Single molecule detection (SMD) of a new perylene dye containing a terminal NH 2 group, n ‐butylimidoethylenamineperylene (PTCD‐NH 2 ), adsorbed on colloidal silver and silver island films was achieved using surface‐enhanced resonance Raman scattering (SERRS). This work represents the first comparative SERRS study where SMD was achieved using two of the most commonly used SERS substrates, colloidal silver and silver island films. SERRS spectra were obtained in colloidal silver solution with analyte concentrations varying from 10 −6 to 10 −12 M and also from silver sols dispersed and dried on polysilane‐coated substrates. SERRS on silver islands was obtained by vacuum evaporation of a 6 nm mass thickness silver overlayer on to a Langmuir–Blodgett (LB) monolayer containing 1, 10 and 100 dye molecules per µm 2 of surface area. The LB technique is ideally suited to obtain spatially resolved spectra of single molecules dispersed in the matrix of a fatty acid, as is used here to obtain SERRS from a few dye molecules found within the area of illumination. The characteristic fundamental vibrational wavenumbers observed in the single molecule SERRS spectra were unequivocally assigned with the help of their first overtones and combinations. Copyright © 2002 John Wiley & Sons, Ltd.