Figure 22.

(A) Experimentally determined atomic H/C ratios for representative ILs at the IL–vapor interface. Reproduced with permission from ref (79). Copyright 2001 Royal Society of Chemistry. (B) Definition of C_m and C_b vectors in [C₄MIM] cation and (C) preferential distributions of [C₄MIM] cations, characterized with bivariate orientations of C_m and C_b vectors, at the IL–vapor interface for simulation systems containing varied numbers of [C₄MIM][PF₆] ion pairs on the graphene surface. The notations →, ↑, and ↓ correspond to C_m and C_b vectors being parallel and perpendicular to the IL–vapor interface with terminal carbon atoms protruded into the vapor phase and projected into bulk liquids, respectively. Reproduced with permission from ref (645). Copyright 2013 Royal Society of Chemistry. (D) Schematic conformation of [C₄MIM] in the IL–vapor interface. Reproduced with permission from ref (646). Copyright 2012 Royal Society of Chemistry. (E) Fresnel-normalized (symbols) and model-fitted (lines) XRR curves of the IL–vapor interface of [C_nMIM][NTF₂] ILs at specific temperatures. Different colors indicate different surface phases. Curves in two colors denote a transition between surface phases. (F) Electron density profiles (normalized to bulk electron density) obtained from model fits in part E. Reproduced with permission from ref (647). Copyright 2018 National Academy of Sciences. (G) XRR profiles for EAN (Δ), PAN (○), and EAF (□) IL–vapor interface, and for (H) EtAN–vapor interface. Reproduced with permission from ref (629). Copyright 2011 Royal Society of Chemistry. Scattering length density profiles for (I) EAN–vapor and (J) EtAN–vapor interfaces from the slab fit (dotted line), Chebyshev fit (dashed line), and slice fit (solid line) models. Reproduced with permission from ref (364). Copyright 2012 Royal Society of Chemistry.