Abstract
Nonlinear optical responses of a self-assembled monolayer (SAM) containing merocyanine chromophore, 1-alkyl-4-(4-hydroxystyryl) pyridinium bromide (HSP), on gold in water and in ethanol were studied by second-harmonic generation (SHG). The pH dependence of the SHG response clearly showed a solvatochromic characteristic of the merocyanine from a protonated form to a zwitterionic form. A large second-order susceptibility χzzz = 5.0 × 10-1 esu (2.1 × 102 pm/V) was found in a basic solution of ethanol where the merocyanine is in the zwitterionic form. Combination of the SHG and surface plasmon resonance (SPR) spectroscopy measurements also provides us with details of the formation process of the merocyanine SAMs in the ethanol solution of the HSP-terminated-alkyldisulfide, ω, ω′-dithiodi[l-undecyl-4-(4-hydroxystyryl)pyridinium bromide](HSPC11SS). A considerable difference was found in the kinetics between SPR and SHG, because SHG probes the molecules in a noncentrosymmetric fashion on the gold surface while SPR probes the optical thickness of the film. The difference enabled us to separate the chemisorption from the physisorption in the adsorption process. Interestingly, both probes showed slower kinetics in the solution of higher concentration, suggesting association of the disulfide molecules in the solution of high concentration.
| Original language | English |
|---|---|
| Pages (from-to) | 607-613 |
| Number of pages | 7 |
| Journal | Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers |
| Volume | 42 |
| Issue number | 2 A |
| Publication status | Published - Feb 1 2003 |
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All Science Journal Classification (ASJC) codes
- Engineering(all)
- Physics and Astronomy(all)
Cite this
Formation of merocyanine self-assembled monolayer and its nonlinear optical properties probed by second-harmonic generation and surface plasmon resonance. / Tsuboi, Kazuma; Seki, Kazuhiko; Ouchi, Yukio; Fujita, Katsuhiko; Kajikawa, Kotaro.
In: Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, Vol. 42, No. 2 A, 01.02.2003, p. 607-613.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Formation of merocyanine self-assembled monolayer and its nonlinear optical properties probed by second-harmonic generation and surface plasmon resonance
AU - Tsuboi, Kazuma
AU - Seki, Kazuhiko
AU - Ouchi, Yukio
AU - Fujita, Katsuhiko
AU - Kajikawa, Kotaro
PY - 2003/2/1
Y1 - 2003/2/1
N2 - Nonlinear optical responses of a self-assembled monolayer (SAM) containing merocyanine chromophore, 1-alkyl-4-(4-hydroxystyryl) pyridinium bromide (HSP), on gold in water and in ethanol were studied by second-harmonic generation (SHG). The pH dependence of the SHG response clearly showed a solvatochromic characteristic of the merocyanine from a protonated form to a zwitterionic form. A large second-order susceptibility χzzz = 5.0 × 10-1 esu (2.1 × 102 pm/V) was found in a basic solution of ethanol where the merocyanine is in the zwitterionic form. Combination of the SHG and surface plasmon resonance (SPR) spectroscopy measurements also provides us with details of the formation process of the merocyanine SAMs in the ethanol solution of the HSP-terminated-alkyldisulfide, ω, ω′-dithiodi[l-undecyl-4-(4-hydroxystyryl)pyridinium bromide](HSPC11SS). A considerable difference was found in the kinetics between SPR and SHG, because SHG probes the molecules in a noncentrosymmetric fashion on the gold surface while SPR probes the optical thickness of the film. The difference enabled us to separate the chemisorption from the physisorption in the adsorption process. Interestingly, both probes showed slower kinetics in the solution of higher concentration, suggesting association of the disulfide molecules in the solution of high concentration.
AB - Nonlinear optical responses of a self-assembled monolayer (SAM) containing merocyanine chromophore, 1-alkyl-4-(4-hydroxystyryl) pyridinium bromide (HSP), on gold in water and in ethanol were studied by second-harmonic generation (SHG). The pH dependence of the SHG response clearly showed a solvatochromic characteristic of the merocyanine from a protonated form to a zwitterionic form. A large second-order susceptibility χzzz = 5.0 × 10-1 esu (2.1 × 102 pm/V) was found in a basic solution of ethanol where the merocyanine is in the zwitterionic form. Combination of the SHG and surface plasmon resonance (SPR) spectroscopy measurements also provides us with details of the formation process of the merocyanine SAMs in the ethanol solution of the HSP-terminated-alkyldisulfide, ω, ω′-dithiodi[l-undecyl-4-(4-hydroxystyryl)pyridinium bromide](HSPC11SS). A considerable difference was found in the kinetics between SPR and SHG, because SHG probes the molecules in a noncentrosymmetric fashion on the gold surface while SPR probes the optical thickness of the film. The difference enabled us to separate the chemisorption from the physisorption in the adsorption process. Interestingly, both probes showed slower kinetics in the solution of higher concentration, suggesting association of the disulfide molecules in the solution of high concentration.
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M3 - Article
AN - SCOPUS:0038005524
VL - 42
SP - 607
EP - 613
JO - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
JF - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
SN - 0021-4922
IS - 2 A
ER -