Voltage-induced modulation of interfacial ionic liquids measured using surface plasmon resonant grating...

Area of Science:

• Electrochemistry
• Materials Science
• Physical Chemistry

Background:

• Ionic liquids (ILs) exhibit unique dielectric properties at electrode interfaces.
• Understanding the electro-optic modulation of ILs is crucial for advanced electrochemical devices.
• The Pockels effect influences the refractive index of ILs under an electric field.

Purpose of the Study:

• To utilize surface plasmon resonant metal gratings for probing the dielectric response of ILs.
• To investigate the electro-optic modulation of ILs at electrode interfaces.
• To quantify the electrical double layer (EDL) thickness and refractive index changes.

Main Methods:

• Employing surface plasmon resonant metal gratings to induce and detect dielectric responses.
• Measuring shifts in resonant angle (Δϕ) correlated with refractive index changes (Δnlocal).
• Utilizing finite difference time domain simulations to analyze plasmon resonance shifts and EDL characteristics.

Main Results:

• Observed electro-optic modulation of ILs via Pockels effect, confirmed by comparison with D2O and benzene.
• Quantified local index changes induced by electrostatic ion accumulation within the EDL.
• Determined effective EDL thickness and refractive index changes by analyzing both wavelength and intensity shifts.

Conclusions:

• The developed surface plasmon resonance technique effectively probes IL dielectric response and EDL dynamics.
• This method offers a versatile tool for studying potential-induced ordering and rearrangement of ionic species.
• Potential applications include advanced electrochemical sensors and energy storage systems.