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Stern and Diffuse Layer Interactions during Ionic Strength Cycling

Ma, Emily and Kim, Jeongmin and Chang, HanByul and Ohno, Paul E. and Jodts, Richard J. and Miller, Thomas F., III and Geiger, Franz M. (2021) Stern and Diffuse Layer Interactions during Ionic Strength Cycling. Journal of Physical Chemistry C, 125 (32). pp. 18002-18014. ISSN 1932-7447. doi:10.1021/acs.jpcc.1c04836.

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Second harmonic generation amplitude and phase measurements are acquired in real time from fused silica:water interfaces that are subjected to ionic strength transitions conducted at pH 5.8. In conjunction with atomistic modeling, we identify correlations between structure in the Stern layer, encoded in the total second-order nonlinear susceptibility, χ_(tot)^(2), and in the diffuse layer, encoded in the product of χ_(tot)^(2) and the total interfacial potential, Φ(0)_(tot). The χ_(tot)^(2):Φ(0)_(tot) correlation plots indicate that the dynamics in the Stern and diffuse layers are decoupled from one another under some conditions (large change in ionic strength), while they change in lockstep under others (smaller change in ionic strength) as the ionic strength in the aqueous bulk solution varies. The quantitative structural and electrostatic information obtained also informs on the molecular origin of hysteresis in ionic strength cycling over fused silica. Atomistic simulations suggest a prominent role of contact ion pairs (as opposed to solvent-separated ion pairs) in the Stern layer. Those simulations also indicate that net water alignment is limited to the first 2 nm from the interface, even at 0 M ionic strength, highlighting water’s polarization as an important contributor to nonlinear optical signal generation.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ma, Emily0000-0002-7922-9208
Ohno, Paul E.0000-0003-4192-1888
Miller, Thomas F., III0000-0002-1882-5380
Geiger, Franz M.0000-0001-8569-4045
Additional Information:© 2021 American Chemical Society. Received 1 June 2021. Revised 20 July 2021. Published online 5 August 2021. Published in issue 19 August 2021. Published as part of The Journal of Physical Chemistry virtual special issue “125 Years of The Journal of Physical Chemistry”. This work was supported by the US National Science Foundation (NSF) under its graduate fellowship research program (GRFP) award to P.E.O. P.E.O. also acknowledges support from the Northwestern University Presidential Fellowship. F.M.G. gratefully acknowledges support from the NSF through Award CHE-1464916 and a Friedrich Wilhelm Bessel Prize from the Alexander von Humboldt Foundation. Parts of this work were also supported by DARPA through the Army Research Office Chemical Sciences Division under Award W911NF1910361. The authors declare no competing financial interest.
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Northwestern UniversityUNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Defense Advanced Research Projects Agency (DARPA)UNSPECIFIED
Army Research Office (ARO)W911NF1910361
Subject Keywords:Interfaces, Ionic strength, Layers, Silica, Ions
Issue or Number:32
Record Number:CaltechAUTHORS:20210830-230029026
Persistent URL:
Official Citation:Stern and Diffuse Layer Interactions during Ionic Strength Cycling Emily Ma, Jeongmin Kim, HanByul Chang, Paul E. Ohno, Richard J. Jodts, Thomas F. Miller, and Franz M. Geiger The Journal of Physical Chemistry C 2021 125 (32), 18002-18014 DOI: 10.1021/acs.jpcc.1c04836
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110629
Deposited By: George Porter
Deposited On:31 Aug 2021 15:44
Last Modified:02 Sep 2021 17:20

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