Title

Large molecular third-order optical nonlinearities in polarized carotenoids

Abstract

Garito and co-workers have suggested a mechanism to dramatically increase the second hyperpolarizability, γ, in linear π-electron-conjugated molecules. Polarization is introduced that leads to a difference between the dipole moments of the molecule's ground state and excited state. Here a series of carotenoids was examined that had increasing intramolecular charge transfer (ICT) from the polyenic chain to the acceptor moiety in the ground state, and γ was measured for these compounds as a function of wavelength by third-harmonic generation. The compound with the greatest ICT exhibited a 35- fold enhancement of γ(max) (the γ measured at the peak of the three-photon resonance) relative to the symmetric molecule β-carotene, which itself has one of the largest third-order nonlinearities known. Stark spectroscopic measurements revealed the existence of a large difference dipole moment, Δμ, between the ground and excited state. Quantum-chemical calculations underline the importance of interactions involving states with large δμ.

Publication Date

5-23-1997

Publication Title

Science

Volume

276

Issue

5316

Number of Pages

1233-1236

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1126/science.276.5316.1233

Socpus ID

10744227954 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/10744227954

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