Two-Photon Absorption Spectrum of Non-Centrosymmetric Molecules
Spectral shape of two-photon absorption of non-centrosymmetric molecules is reviewed in view of correspondence of their one-photon absorption spectrum. Theoretical formula for the two-photon absorption cross section is re-examined with showing each approximation steps and is classified into Dipolar, Three-state, and Cross terms. Experimentally obtained two-photon absorption spectra for more than 20 non-centrosymmetric molecules with variety of chemical structures (p-phenyl anilines, azobenzenes, stilbenes, π-extended diacetylenes, heptamethines, lanthanoid complexes, π-extended BODIPY’s, organosilicons, organophosphoruses, and tetrakis(phenylethynyl)benzenes) are discussed in relation to their one-photon absorption spectrum. The component analysis of two-photon absorption spectrum based on ab initio molecular orbital calculation clarified that the destructive interference of Dipolar term and Three-state term causes the disagreement between the one- and two-photon absorption spectra.
Keywords: two-photon absorption, spectrum, non-centrosymmetric, dipolar, π-conjugate molecule