J. Phys. Chem. 1982, 86, 3391-3395 - Adsorption On Silver and Gold Sols - Metodo Lee-Meisel
J. Phys. Chem. 1982, 86, 3391-3395 - Adsorption On Silver and Gold Sols - Metodo Lee-Meisel
J. Phys. Chem. 1982, 86, 3391-3395 - Adsorption On Silver and Gold Sols - Metodo Lee-Meisel
Several negatively charged dyes were investigated for their possible adsorption on the surface of silver and
gold colloidal particles. Those dyes that were found to adsorb on the particles were then checked for surface
enhancement of Raman scattering. Highly efficient surface-enhancedRaman scattering (SERS) was observed
from a carbocyanine dye in both sols. Excitation-dependence studies as well as adsorption studies confirm
the SEW nature of the Raman spectra obtained. The dye is probably aggregated on adsorption and is probably
attached through the naphthalene side moiety to the surface. Less efficient SERS was also observed for copper
phthalocyanine.
AN
particle6 out of which -8% are surface atoms (assuming
spherical particles and 1.38-A atomic radius for Ag). Ad-
dition of 2 X lo6 M of BICC to the sol results only in some
N broadening of the sol's spectrum with hardly any absorp-
tion by dye free in the solution (Figure 2b). We could
estimate that less than 10% of the dye is free in the bulk
of the solution under the experimental conditions of Figure
2b. The dye could easily be recovere'd from the particle's
surface either by addition of alcohols such as 2-propanol
or 2-methyl-2-propanol (Figure 2c) or by coagulation of the
M
/ -
SO3 Na+
sol with high concentrations of electrolytes (it was, how-
~~
(14) (a) W. West and S. Pearce, J.Phys. Chem., 69, 1894 (1965); (b)
J. P. Webb, F. G. Webster, and B. E. Plourde, Eastmun Org. Chem. Bull.,
CuTSPc 46, 3 (1974).
Adsorption of Dyes on Silver and Gold Sols The Journal of Physical Chemistry, Vol. 86, No. 17, 1982 3393
800 .AI. 1
d 700
*
;m
1.0 1 I-
z
500
400
I I I 1149,
350
* mt
w
-I
"V
400 500 600 700 800 900
g I P
250
A , nm
Flgure 2. Absorption spectra of BICC in the presence of Ag sol: (a)
M PVA-stabilized silver sol only; (b) 2 X lo4 M BICC in the 200
presence of 0.9 X M silver sol; (c) same as b after 1:l dilution
with P-methyl-2-propanol; (d) same as c wtthout Ag sol. Optical path AV, crn-'
for a and b is 0.1 cm; for ca and d, 1 cm.
Figure 4. Raman spectra of BICC dye in powder form (a) and 3 X
06-- 7 -
__- ~~