Browsing by Author "Nosaka, Yugo"

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Giant Pockels effect of polar organic solvents and water in the electric double layer on a transparent electrode
(2017-01-01)
Kanemaru, Hironori
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Yukita, Shunpei
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Namiki, Hajime
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Nosaka, Yugo
;
Kobayashi, Takayoshi
The Pockels effect of polar organic solvents and water within the electric double layer (EDL) on an indium-tin-oxide (ITO) electrode is studied to find that water has the largest Pockels coefficient (230 pm V-1), followed in order by methanol (200 pm V-1), ethanol (84 pm V-1), and dimethyl sulfoxide (DMSO) (20 pm V-1). Electrolyte solutions of water and methanol have nearly the same magnitude of Pockels coefficient, while ethanol and DMSO solutions exhibit two and ten times smaller Pockels coefficients than the methanol solution, respectively. The Pockels coefficient scales well with the hydrogen-bond strength (or average cluster size) divided by the solvent viscosity. This suggests that hydrogen bonding and viscosity play crucial roles in the mechanism of the Pockels effect of these liquids.
Pockels effect of water in the electric double layer at the interface between water and transparent electrode
(2007-02-01)
Tokunaga, Eiji
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Nosaka, Yugo
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Hirabayashi, Masashi
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Kobayashi, Takayoshi
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先進超快雷射研究中心
We have obtained the first experimental evidence for the Pockets effect of water, which is induced by a high electric field in the electric double layer (EDL) on the water transparent electrode interface. The electric-field induced energy shift of the visible interference fringes of a 300 nm indium-tin-oxide (ITO) electrode layer is observed, indicating a negative refractive index change at the interface. Numerical calculation reproduces well the experimental observation, showing that the signal mainly originates from water in the EDL. The Pockets constants of water are estimated to be r(33) = 5.1 x 100 pm/V and r(13) = 1.7 x 100 pm/V. The large anisotropy of the Pockets effect of water is deduced from the incidence angle dependence of the p-polarization signal. At the same time, the ITO shows a blue shift of the band gap in the UV due to the band population effect in the space charge layer. The plasma frequency in the near IR is also expected to increase due to the band population effect, since the ITO has a high doped carrier population close to metal. A negative refractive index change in the ITO space charge layer is induced from both effects, but its effect on the signal is estimated to be much smaller than that of the negative refractive index change of water in the EDL. (c) 2006 Published by Elsevier B.V.