Structural definition of the BIL and DL: a new universal methodology to rationalize non-linear χ(2)(ω) SFG signals at charged interfaces, including χ(3)(ω) contributions. Issue 7 (2nd February 2018)

• Record Type: Journal Article
• Authors: Pezzotti, Simone; Galimberti, Daria Ruth; Shen, Y. Ron; Gaigeot, Marie-Pierre
• Is Part Of: Physical chemistry chemical physics. Volume 20:Issue 7(2018)
• Page Start: 5190
• Page End: 5199
• Publication Date: 2018-02-02
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c7cp06110b
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : BIL (Binding Interfacial Layer) and DL (Diffuse Layer) at aqueous interfaces: universal structural definitions, deconvolution of their SFG signals and χ 3 contribution. Abstract : This work provides unambiguous definitions from theoretical simulations of the two interfacial regions named the BIL (binding interfacial layer) and DL (diffuse layer) at charged solid/water and air/water interfaces. The BIL and DL nomenclature follows the pioneering work of Wen et al. [ Phys. Rev. Lett. 2016, 116, 016101]. Our definitions are based on the intrinsic structural properties of water only. Knowing the BIL and DL interfacial regions, one is then able to deconvolve the χ (2) ( ω ) non-linear SFG (sum frequency generation) response into χ (2)BIL( ω ) and χ (2)DL( ω ) contributions, thus providing a detailed molecular interpretation of these signals and of the measured total SFG. We furthermore show that the χ (2)DL( ω ) spectrum arises from the χ (3) ( ω ) non-linear third order contribution of bulk liquid water, here calculated for several charged interfaces and shown to be universal. The χ (2)DL( ω ) contribution therefore has the same origin in terms of molecular normal modes at any charged interface. The molecular interpretation of χ (2)BIL( ω ) is hence at the heart of the unambiguous molecular comprehension and interpretation of the measured total SFG signal at any charged interface.