Trimeric associate of EMImBF 4 ionic liquid at Au(111), Bi(111), and C(0001) surfaces: interaction energy, geometry, and spectra

The ion-ion correlation is the reason for the characteristic layering at an ionic liquid-electrode interface. The hierarchy of interface models, which includes the ion-ion correlation, starts with a simple ionic pair near a model surface. Larger associates of mixed composition account for both repulsive and attractive interactions between ions. In this work, we have studied one of such associates made of three 1-methyl-3-ethyl-imidazolium tetrafluoroborate ionic pairs at Au(111), Bi(111), and C(0001) surface models using density functional theory calculations. We have focused on a detailed analysis of the interfacial geometry and interaction strength under an applied field imitating electrochemical conditions. To bridge the computational results with experimental data from the literature, we have modeled the X-ray photoelectron spectra of B(1s), C(1s), N(1s), and F(1s) based on the charge distribution analysis.