specific. There appears to be a dependence on flow rate as well, given that the time traces shown in this work were recorded using a flow rate of 10 ml min -1 , whereas our previous study was carried out at 5 mL min -1 and showed less of a non-monotonic variation in the SHG signal intensity at early times when compared to the present work. These results will be pursued further in upcoming work that is beyond the scope of this study.