Reply To The 'Comment On "Bi-Layering At Ionic Liquid Surfaces: A Sum-Frequency Generation Vibrational Spectroscopy- And Molecular Dynamics Simulation-Based Study"' By M. Deutsch, O. M. Magnussen, J. Haddad, D. Pontoni, B. M. Murphy And B. M. Ocko, Phys. Chem. Chem. Phys., 2021, Doi:; 10.1039/D0cp04882h

In our recent paper titled "Bi-layering at ionic liquid surfaces: a sum-frequency generation vibrational spectroscopy- and molecular dynamics simulation-based study" co-authored by T. Iwahashi, T. Ishiyama, Y. Sakai, A. Morita, D. Kim, and Y. Ouchi, Phys. Chem. Chem. Phys., 2020, 22, 12565 (hereafter referred to as IW), the sum-frequency (SF) spectra for a homologous series of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C(n)mim][TFSA] n = 4, 6, 8, 10, and 12) were reported. In particular, a clear decrease in the SF signals from the [TFSA](-) anions with increasing chain length of the [C(n)mim](+) cation (Fig. 5 of IW) was explained in terms of "head-to-head" bi-layer formation at the air/ionic liquid (IL) interface. A comment by M. Deutsch et al. (hereafter referred to as DE) questioned this report, claiming that our proposed structure is not consistent with a multilayered electron density (ED) profile obtained by X-ray reflectivity (XR).