Measurements of molecular optical Hyperpolarisabilities using Hyper-Rayleigh Scattering

Abstract

In this paper we report on new experiments of Hyper-Rayleigh Scattering (HRS) in solution, i.e. incoherent second harmonic light scattered from solutions illuminated by intense (IR) laser pulses. The HRS-technique, developed recently1, allows an accurate and easy determination of first order hyperpolarisabilities β of molecules. The great advantage of HRS as compared to electric field induced second harmonic generation (EFISHG, the other technique to determine β) is the absence of an orienting electric field to reduce the intrinsic symmetry of an isotropic solution. As a consequence data on the dipole moments are not needed and local field correction factors are unnecessary. HRS allows the determination of β of ionic species and will be the method of choice for the investigation of apolar molecules where p originates from octopolar charge distributions.2