Electrical fluctuations: a source of microscopic information

NMR relaxation time and electric field gradient fluctuations

NMR (Nuclear Magnetic Relaxation) relaxometry is a powerful tool to explore the structure and dynamics of liquids. We use molecular simulation to analyze the fluctuations of the electric field gradient experienced by nuclei, that determine the NMR relaxation times T1 and T2 of quadrupolar nuclei. More specifically, we are interested in the dynamics of water around alkaline and alkaline earth cations, as well as ion dynamics in silicate glasses.

• Funding : ENS, ERC SENSES
• PHENIX : Mathieu Salanne, Antoine Carof
• Collaborations : Thibault Charpentier (CEA)

Selected publications

• Accurate Quadrupolar NMR Relaxation Rates of Aqueous Cations from Classical Molecular Dynamics
  A. Carof, M. Salanne, T. Charpentier et B. Rotenberg, J. Phys. Chem. B, 118, 13252 (2014).
• On the microscopic fluctuations driving the NMR relaxation of quadrupolar ions in water
  A. Carof, M. Salanne, T. Charpentier, B. Rotenberg, J. Chem. Phys., 143, 194504 (2015).
• NMR Relaxation Rates of Quadrupolar Aqueous Ions from Classical Molecular Dynamics Using Force-Field Specific Sternheimer Factors
  I. Chubak, L. Scalfi, A. Carof, B. Rotenberg, J. Chem. Theory Comput., 17, 6006 (2021)
• Quadrupolar ²³Na⁺ NMR Relaxation as a Probe of Subpicosecond Collective Dynamics in Aqueous Electrolyte Solutions
  I. Chubak, L. Alon, E. Silletta, G. Madelin, A. Jerschow, and B. Rotenberg. Nature Commun., 14, 84 (2023)

Charge fluctuations in capacitors

Charge fluctuations in a capacitor, if one knows how to interpret them, encode informations on the microscopic structure and dynamics of the electrode-electrolyte interface. We have recently demonstrated the interest of analyzing these fluctuations in molecular simulations to compute the differential capacitance and to investigate the evolution of the interface with applied voltage. This opens a wide range of perspectives and we would like to develop this approach for various problems in the next years.

• Funding : ANR, France-Berkeley Fund, ERC SENSES
• PHENIX : M. Salanne
• Collaborations : David Chandler (Berkeley), Paul Madden (Oxford), Céline Merlet (Cambridge), David Limmer (Princeton), Rene van Roij (Utrecht)

Selected publications

• Charge Fluctuations in Nanoscale Capacitors
  D.T. Limmer, C. Merlet, M. Salanne, D. Chandler, P.A. Madden, R. van Roij et B. Rotenberg , Phys. Rev. Lett., 111, 106102 (2013)
• The Electric Double Layer Has a Life of Its Own
  C. Merlet, D.T. Limmer, M. Salanne, R. van Roij, P.A. Madden, D. Chandler et B. Rotenberg, J. Phys. Chem. C, 118, 12891 (2014).
• Charge fluctuations from molecular simulations in the
  constant-potential ensemble
  L. Scalfi, D.T. Limmer, A. Coretti, S. Bonella, P.A. Madden, M. Salanne,
  B. Rotenberg Phys. Chem. Chem. Phys., 22, 10480 (2020)
• Field-dependent ionic conductivities from generalized
  fluctuation-dissipation relations
  D. Lesnicki, C.Y. Gao, B. Rotenberg, D.T. Limmer, Phys. Rev. Lett., 124, 206001 (2020)
• Microscopic origin of the effect of substrate metallicity on interfacial free energies
  L. Scalfi, B. Rotenberg, PNAS, 118 e2108769118 (2021)