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Title: Phase-referenced nonlinear spectroscopy of the α-quartz/water interface

Probing the polarization of water molecules at charged interfaces by second harmonic generation spectroscopy has been heretofore limited to isotropic materials. Here we report non-resonant nonlinear optical measurements at the interface of anisotropic z-cut α-quartz and water under conditions of dynamically changing ionic strength and bulk solution pH. We find that the product of the third-order susceptibility and the interfacial potential, χ (3) × Φ(0), is given by (χ1 (3)–iχ2 (3)) × Φ(0), and that the interference between this product and the second-order susceptibility of bulk quartz depends on the rotation angle of α-quartz around the z axis. Our experiments show that this newly identified term, iχ (3) × Φ(0), which is out of phase from the surface terms, is of bulk origin. Lastly, the possibility of internally phase referencing the interfacial response for the interfacial orientation analysis of species or materials in contact with α-quartz is discussed along with the implications for conditions of resonance enhancement.
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ;  [1] ;  [4]
  1. Northwestern Univ., Evanston, IL (United States)
  2. Northwestern Univ., Evanston, IL (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  4. Columbia Univ., New York, NY (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2041-1723
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
74 ATOMIC AND MOLECULAR PHYSICS; optical spectroscopy; surface spectroscopy
OSTI Identifier: