A New Imaginary Term in the 2nd Order Nonlinear Susceptibility from Charged Interfaces
Abstract
Non-resonant second harmonic generation phase and amplitude measurements obtained from the silica:water interface at varying pH and 0.5 M ionic strength point to the existence of a nonlinear susceptibility term, which we call chi(3)X, that is associated with a 90 deg phase shift. Including this contribution in a model for the total effective second-order nonlinear susceptibility produces reasonable point estimates for interfacial potentials and second-order nonlinear susceptibilities when chi(3)Xis about 1.5 times chi(3)water. A model without this term and containing only traditional chi(2) and chi(3) terms cannot recapitulate the experimental data. The new model also provides a demonstrated utility for distinguishing apparent differences in the second-order nonlinear susceptibility when the electrolyte is NaCl vs MgSO4, pointing to the possibility of using HD-SHG to investigate ion-specificity in interfacial processes.
Cite
@article{arxiv.2104.02802,
title = {A New Imaginary Term in the 2nd Order Nonlinear Susceptibility from Charged Interfaces},
author = {Emily Ma and Paul E. Ohno and Jeongmin Kim and Yangdongling Dawning Liu and Emilie H. Lozier and Thomas F. Miller and Hong-Fei Wang and Franz M. Geiger},
journal= {arXiv preprint arXiv:2104.02802},
year = {2021}
}
Comments
Pre-edited version, 16 Pages main text, 4 Figures, Supporting Information