scholarly journals Pushing and pulling on OH- and H3O+ with electric fields across water’s surface

2021 ◽  
Author(s):  
Kamal Ray ◽  
Aditya Limaye ◽  
Ka Chon Ng ◽  
Ankur Saha ◽  
Sucheol Shin ◽  
...  
Keyword(s):  
Electric Fields ◽  
Double Layer ◽  
Second Harmonic ◽  
Water Layer ◽  
Dynamics Simulation ◽  
Harmonic Intensity ◽  
Neat Water ◽  
Orientational Response ◽  
Air Interface ◽  
Dipolar Orientation

We use second harmonic generation (SHG) spectroscopy, molecular dynamics simulation, and theoretical modeling to study the response of the neat liquid water-air interface to changes in the potential of an external electrode positioned above the liquid. We observe a parabolic dependence of second harmonic intensity on applied potential. This dependence is reminiscent of bulk-phase electric field induced second harmonic (EFISH) but more complicated because it combines the second-order response of the topmost water layer and the potential dependent response of the interfacial electrical double-layer. Based on the literature values for these contributions, we derive a physical interpretation of our measurements that reveals new insight into the response of the neat water interface to external electric fields. Specifically, we find that the net dipolar orientation of water molecules within the double-layer is primarily responsive to the internal fields generated by the excess surface concentrations of OH- and H3O+ that arise to screen the external potential. Notably, this interpretation implies that the orientational response of water dipoles at the interface can actually oppose the direction of the external field, a subtle effect that is not captured by traditional models.

scholarly journals Pushing and Pulling on OH-and H3O+ with Electric Fields Across Water’s Surface

2021 ◽  
Author(s):  
kamal ray ◽  
Aditya Limaye ◽  
Ankur Saha ◽  
Ka Chon Ng ◽  
Adam Willard ◽  
...  
Keyword(s):  
Electric Fields ◽  
Second Harmonic ◽  
Ionic Species ◽  
Dynamics Simulation ◽  
Dipole Orientation ◽  
Harmonic Intensity ◽  
Air Interface ◽  
Excess Surface ◽  
Internal Bias ◽  
Pushing And Pulling

<p>We use second harmonic generation spectroscopy, molecular dynamics simulation, and theoretical modeling to study the response of the neat liquid water-air interface to changes in the potential of an external electrode positioned above the liquid. We observe a parabolic dependence of second harmonic intensity on applied potential, indicating that water’s net interfacial dipole responds linearly. We also observe a minimum intensity when the potential is tuned to a specific positive value. Interpreting this minimum based on the macroscopic electrostatic potential profile yields misleading physical conclusions because it neglects the internal bias exerted on molecular orientations by the excess surface concentrations of OH<sup>-</sup> or H<sub>3</sub>O<sup>+</sup>. We thus find that water’s net interfacial dipole orientation is primarily responsive to the effects of these ionic species rather than the external electric field. </p>

scholarly journals Pushing and Pulling on OH-and H3O+ with Electric Fields Across Water’s Surface

2021 ◽  
Author(s):  
kamal ray ◽  
Aditya Limaye ◽  
Ankur Saha ◽  
Ka Chon Ng ◽  
Adam Willard ◽  
...  
Keyword(s):  
Electric Fields ◽  
Second Harmonic ◽  
Ionic Species ◽  
Dynamics Simulation ◽  
Dipole Orientation ◽  
Harmonic Intensity ◽  
Air Interface ◽  
Excess Surface ◽  
Internal Bias ◽  
Pushing And Pulling

<p>We use second harmonic generation spectroscopy, molecular dynamics simulation, and theoretical modeling to study the response of the neat liquid water-air interface to changes in the potential of an external electrode positioned above the liquid. We observe a parabolic dependence of second harmonic intensity on applied potential, indicating that water’s net interfacial dipole responds linearly. We also observe a minimum intensity when the potential is tuned to a specific positive value. Interpreting this minimum based on the macroscopic electrostatic potential profile yields misleading physical conclusions because it neglects the internal bias exerted on molecular orientations by the excess surface concentrations of OH<sup>-</sup> or H<sub>3</sub>O<sup>+</sup>. We thus find that water’s net interfacial dipole orientation is primarily responsive to the effects of these ionic species rather than the external electric field. </p>

PRELIMINARY OPTICAL STUDY ON ER FLUIDS

1994 ◽  
Vol 08 (20n21) ◽  
pp. 2921-2933 ◽  
Author(s):  
L. W. ZHOU ◽  
J. F. YE ◽  
R. B. TAO ◽  
Y. TANG ◽  
J. F. PENG ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
Electric Fields ◽  
Nonlinear Optical ◽  
Second Harmonic ◽  
Optical Response ◽  
Optical Study ◽  
Solid States ◽  
Linear And Nonlinear ◽  
Er Fluids

Linear and nonlinear optical study on electrorheological (ER) fluids is reported. The ER fluids under the investigation were glass beads, zeolite and ferroelectrics. The linear optical response of some ER fluids showed sharp changes near critical electric fields. An enhancement of electric field induced second harmonic generations (EFISH) was observed as the function of E2, where E is the external electric field. The said enhancement is considered to be corresponding to a modulation of the material's refractive index associated with the electric field induced polarization of the delocalized electrons. The enhanced nonlinear optical response on the transition between liquid and solid states can be related to the phase transition in ER fluids.

scholarly journals On the Emergence of Electric Fields at the Water-C12E6 Surfactant Interface

2021 ◽  
Author(s):  
Rahul Gera ◽  
Huib Bakker ◽  
Ricardo Franklin ◽  
Uriel N. Morzan ◽  
Gabriele Falciani ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Md Simulations ◽  
Mutual Orientation ◽  
Kelvin Probe ◽  
Sum Frequency ◽  
Hydrogen Bond Strength ◽  
Air Interface ◽  
Harvesting Systems ◽  
Probe Measurements

We study the properties of the interface of water and the surfactant Hexaethylene Glycol Monododecyl Ether (C12E6)<br>with a combination of Heterodyne-Detected Vibrational Sum Frequency Generation (HD-VSFG), Kelvin-Probe measurements, and Molecular Dynamics (MD) simulations. We observe that the addition of C12E6 close to the critical micelle concentration (CMC), induces a drastic hydrogen bond strength enhancement of the water molecules close to the interface, as well as a flip in their net orientation. The mutual orientation of the water and C12E6 molecules, leads to the emergence of a broad (~ 3 nm) interface with a large electric field of ~ 1V/nm, as evidenced by the Kelvin-Probe measurements and MD simulations. Our findings may open the door for the design of novel electric-field tuned catalytic and light harvesting systems anchored at water-surfactant air interface. <br>

scholarly journals Manuscript-C-dots assembly at interface-041020.pdf

2020 ◽  
Author(s):  
Amin Reza Zolghadr ◽  
Behnam Rostami
Keyword(s):  
Self Assembly ◽  
Carbon Dots ◽  
Sodium Dodecyl ◽  
Surface Region ◽  
Systematic Investigation ◽  
Dynamics Simulation ◽  
Surface Tension Gradient ◽  
Bivariate Analysis ◽  
Air Interface ◽  
Sds Surfactant

We describe a systematic investigation of carbon dots (C-dots) assemblies fabricated at the liquid/air interface because of the surface tension gradient. This gradient is originally created by capillary action and increased by addition of sodium dodecyl sulfate (SDS) surfactant or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) phospholipid to the surface of C-dots aqueous mixture. The arrangement of carbon dots in liquid bulk phase (before self-assembly) and at the surface region (after self-assembly) was examined by TEM microscopy. The presence of SDS surfactant and POPC phospholipid at the air/water interface induced the C-dots compression. In addition, molecular dynamics simulation was conducted to obtain the structure of C-dots at liquid/vapor interface. The orientation of C-dots is evaluated quantitatively at water/vapor surface by using bivariate analysis.

Polymerization of Isobutylene Initiated by Laser Vaporization of Metal Targets

1992 ◽  
Vol 285 ◽  
Author(s):  
Walter Vann ◽  
George M. Daly ◽  
M. Samy El-shall
Keyword(s):  
Electric Fields ◽  
Laser Energy ◽  
Second Harmonic ◽  
Polymeric Materials ◽  
Reaction Chamber ◽  
Laser Vaporization ◽  
Viscous Liquids ◽  
Molecular Weights ◽  
Full Characterization ◽  
Powerful Approach

ABSTRACTA novel technique involving the initiation of polymerization using laser vaporization of metal targets is being explored. In the experiment, metal ions such as Ti+, Zr+, Ag+ are generated in the gas phase by pulsed laser vaporization/ionization of a metal target using the second harmonic of a Nd:YAG laser (532 nm). The ions are pulled toward a monomer liquid(isobutylene which can only be polymerized by cationic mechanisms) by applyingappropriate electric fields across the reaction chamber. Under different experimentalconditions (temperature, pressure of a carrier gas, laser energy, electric field strength, reaction time) different polymeric products (viscous liquids or solids) were obtained with average molecular weights ranging from 200 to greater than 106. Full characterization of these materials is currently in progress. This technique could lead to a powerful approach for the synthesis of a wide variety of polymeric materials with unique properties such as stability, strength and photo and electrical conductivity.

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