The SHG intensity measurements employed in our time-dependent experiments are carried out using the same standard sample cell and flow system described above but at a flow rate of 10 mL min -1 now the interface is probed by the 1035 nm output of a Light Conversion Flint Oscillator (90 fs pulse duration at 80 MHz repetition rate) attenuated to 0.5 W. We use the p-in/pout polarization combination and record the SHG intensity using a time resolution of 100 ms.