Quantum limits of the hyper-Rayleigh scattering susceptibility

摘要

Sum rules have been used to show that there is an upper limit tonmolecular susceptibilities. Such calculations have been applied to thendiagonal part of the second-order susceptibility tensor as measured withnelectric-field-induced second-harmonic generation, and to a variety ofnthird-order measurements. The results show that the off-resonantnsusceptibilities of all molecules measured fall within the calculatednlimits. In this contribution, we show that the most susceptibilitiesnmeasured with hyper Rayleigh scattering (HRS) fall below thentwo-dimensional theoretical limit, and discuss the issue of why somenmolecules appear to break this limit