TY - JOUR
T1 - Surface enhanced Raman spectroscopy
T2 - A re-examination of the role of surface roughness and electrochemical anodization
AU - Schultz, Steven G.
AU - Janik-Czachor, Maria
AU - Van Duyne, R. P.
PY - 1981/3/2
Y1 - 1981/3/2
N2 - To date all surface enhanced Raman spectroscopy (SERS) studies have been carried out on rough metal surfaces. This has resulted in the general impression that surface roughness is an absolute prerequisite for the observation of SERS. In this paper we demonstrate, at least for the case of SERS at the solid-liquid interface (i.e., an electrochemical cell) that neither surface roughness (viz., quasi-spherical particles ≥ 250 Å in diameter) or electrochemical anodization are prerequisites to SERS observation. For the model system, Ag/0.05 M pyridine/0.1 M KCl/ H2O, an enhancement factor of ca. 104 is observed on "smooth", unanodized surfaces implying a maximum roughness contribution to the overall enhancement of only about ca. 102. The observation of SERS on "smooth" surfaces is not restricted to pyridine since it can also be observed in the system Ag/0.005 M Pt(CN)42-/0.1 M SO42-/H2O. These results strongly support the hypothesis that the overall SERS enhancement of 106 is the product of 104 enhancement from a roughness independent mechanism (e.g., image-dipole mechanism) and a 102 enhancement from a roughness dependent mechanism (e.g., the development of geometrically defined electromagnetic resonances near rough solid surfaces - "lightning rod mechanism").
AB - To date all surface enhanced Raman spectroscopy (SERS) studies have been carried out on rough metal surfaces. This has resulted in the general impression that surface roughness is an absolute prerequisite for the observation of SERS. In this paper we demonstrate, at least for the case of SERS at the solid-liquid interface (i.e., an electrochemical cell) that neither surface roughness (viz., quasi-spherical particles ≥ 250 Å in diameter) or electrochemical anodization are prerequisites to SERS observation. For the model system, Ag/0.05 M pyridine/0.1 M KCl/ H2O, an enhancement factor of ca. 104 is observed on "smooth", unanodized surfaces implying a maximum roughness contribution to the overall enhancement of only about ca. 102. The observation of SERS on "smooth" surfaces is not restricted to pyridine since it can also be observed in the system Ag/0.005 M Pt(CN)42-/0.1 M SO42-/H2O. These results strongly support the hypothesis that the overall SERS enhancement of 106 is the product of 104 enhancement from a roughness independent mechanism (e.g., image-dipole mechanism) and a 102 enhancement from a roughness dependent mechanism (e.g., the development of geometrically defined electromagnetic resonances near rough solid surfaces - "lightning rod mechanism").
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U2 - 10.1016/0039-6028(81)90069-8
DO - 10.1016/0039-6028(81)90069-8
M3 - Article
AN - SCOPUS:0002230972
VL - 104
SP - 419
EP - 434
JO - Surface Science
JF - Surface Science
SN - 0039-6028
IS - 2-3
ER -