Study of second-order nonlinear hyperpolarisability of all-trans-\beta-carotene in solutions by linear spectroscopic technique

This paper demonstrates the second-order nonlinear hyperpolarisability \gamma of all-trans-\beta-carotene in different solvents by linear spectroscopic technique that is based on resonance Raman scattering and UV--VIS (Ultraviolet-visible) absorption spectroscopy. Owing to the two-level model well describing the link that exists between the resonance Raman scattering and stimulated Raman scattering, the stimulated Raman polarisability \alpha_\rm R can be calculated through the two-photon resonance system. The value of \gamma of all-trans-\beta-carotene in carbon bisulfide solution is 6.435\times 10^-33 esu (1 esu of resistance = 8.98755\times10^11~\Omega) that is close to the true value, because the solution of all-trans-\beta-carotene in carbon bisulfide satisfies the rigid resonance Raman scattering condition. This method is expected to be worthy of applications to measure the second-order nonlinear hyperpolarisability of a conjugate organic molecule.