Deciphering second harmonic generation signals
Yann Foucaud, Bertrand Siboulet, Magali Duvail, Alban Jonchère, Olivier Diat, Rodolphe Vuilleumier, Jean‐François Dufrêche
Abstract
method developed here shows that a bulk quadrupole contribution significantly overwhelms the interface dipole term in the purely interfacial induced second-order polarisation for water/air interfaces. The obtained simulated SHG responses are in unprecedented agreement with the experimental signal. This work not only paves the road for the prediction of SHG response from more complex interfaces of all types, but also suggests new insights in the interpretation of the SHG signal at a molecular level. In particular, it highlights the modest influence of the molecular orientation and the high significance of the bulk quadrupole contribution, which does not depend on the interface, in the total experimental response.