Abstract
Calculations of the electronic and vibrational second hyperpolarizabilities of various quadrupolar π-conjugated molecules performed at the ab initio Hartree-Fock level of approximation show that the vibrational contribution is large for most nonlinear optical phenomena. As for unsubstituted π-conjugated compounds, the Raman term which contributes to the dc-Kerr and degenerate four-wave mixing phenomena is of the same order of magnitude as the static electronic counterpart. The term related to the infrared and hyper-Raman intensities is substantial and, in the case of a squaraine dye, dictates the sign of the global response. This infrared-hyper-Raman term which is often negligible for unsubstituted compounds contributes substantially to the vibrational dc-Kerr and electric field-induced second harmonic generation responses.
Original language | English |
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Pages (from-to) | 247-254 |
Number of pages | 8 |
Journal | Journal of optics. A: Pure and applied optics |
Volume | 2 |
Issue number | 4 |
DOIs | |
Publication status | Published - 1 Jul 2000 |