Molecular dynamics evaluation at liquid-solid interfaces by Optical Kerr Effect spectroscopy

Nonlinear optical spectroscopies of confined liquids and sum- and difference- frequency mixing spectroscopies at interfaces are widespread methods to determine the molecular dynamics of fluids in the vicinity of solid surfaces. In this work, we introduce a new technique based on the Optical Kerr Effect Spectroscopy (OKE), carried out by the total internal reflection of both pump and probe beams at the solid/liquid interface. This new technique, Surface Time-Resolved OKE (STROKE), provides a unique tool complementary to the methods mentioned above. This ultrafast spectroscopy relies on the optical response probed after the anisotropy generated by the pump pulse, due to the induced molecular alignment in the region of its evanescent field. We report on the first results of this approach in the SF11 glass/CS₂ system and compare the observed dynamic with OKE results from confined liquids in sol-gel nanoporous. We compare the diffusive responses to evaluate confinement and wall interactions.