Large off-diagonal contribution to the second-order optical nonlinearities of Λ-shaped molecules

Résultats de recherche: Contribution à un journal/une revueArticle

Résumé

The diagonal and off-diagonal tensor components of the first hyperpolarizability of a series of Λ-shaped molecules are compared by means of ab initio and semiempirical molecular orbital calculations. The calculated results are rationalized using expressions derived from a simple valence-bond charge-transfer model in which one ground and two excited state are described as a combination of one valence-bond (VB) and two charge-transfer (CT) states. In addition to the CT character, the angle (2θ) between the two donor (D)/acceptor (A) branches is a key parameter to determine the relative magnitudes between the βxxz and βzzz components. In the VB-2CT model, βxxz presents a maximum value for 2θ = 109.47°, whereas βxxz and μz have the same sign. On the other hand, βzzz decreases monotonically with θ, and its variations with the CT character follow a curve with two extrema like for one-dimensional D/A chromophores. The ab initio and semiempirical calculations as well as the VB-2CT model show that Λ-shaped molecules with large first hyperpolarizability and specific η = βxxzzzz can be designed in order to build phase-matchable second-harmonic generation crystals.

langue originaleAnglais
Pages (de - à)3942-3951
Nombre de pages10
journalJournal of physical chemistry A
Volume107
Numéro de publication19
Les DOIs
étatPublié - 15 mai 2003

Empreinte digitale

Charge transfer
nonlinearity
charge transfer
valence
Molecules
molecules
Orbital calculations
range (extremes)
Molecular orbitals
Chromophores
Harmonic generation
Excited states
chromophores
Tensors
harmonic generations
molecular orbitals
tensors
Crystals
curves
excitation

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title = "Large off-diagonal contribution to the second-order optical nonlinearities of Λ-shaped molecules",
abstract = "The diagonal and off-diagonal tensor components of the first hyperpolarizability of a series of Λ-shaped molecules are compared by means of ab initio and semiempirical molecular orbital calculations. The calculated results are rationalized using expressions derived from a simple valence-bond charge-transfer model in which one ground and two excited state are described as a combination of one valence-bond (VB) and two charge-transfer (CT) states. In addition to the CT character, the angle (2θ) between the two donor (D)/acceptor (A) branches is a key parameter to determine the relative magnitudes between the βxxz and βzzz components. In the VB-2CT model, βxxz presents a maximum value for 2θ = 109.47°, whereas βxxz and μz have the same sign. On the other hand, βzzz decreases monotonically with θ, and its variations with the CT character follow a curve with two extrema like for one-dimensional D/A chromophores. The ab initio and semiempirical calculations as well as the VB-2CT model show that Λ-shaped molecules with large first hyperpolarizability and specific η = βxxz/βzzz can be designed in order to build phase-matchable second-harmonic generation crystals.",
author = "Mingli Yang and Beno{\^i}t Champagne",
year = "2003",
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Large off-diagonal contribution to the second-order optical nonlinearities of Λ-shaped molecules. / Yang, Mingli; Champagne, Benoît.

Dans: Journal of physical chemistry A, Vol 107, Numéro 19, 15.05.2003, p. 3942-3951.

Résultats de recherche: Contribution à un journal/une revueArticle

TY - JOUR

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AU - Champagne, Benoît

PY - 2003/5/15

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N2 - The diagonal and off-diagonal tensor components of the first hyperpolarizability of a series of Λ-shaped molecules are compared by means of ab initio and semiempirical molecular orbital calculations. The calculated results are rationalized using expressions derived from a simple valence-bond charge-transfer model in which one ground and two excited state are described as a combination of one valence-bond (VB) and two charge-transfer (CT) states. In addition to the CT character, the angle (2θ) between the two donor (D)/acceptor (A) branches is a key parameter to determine the relative magnitudes between the βxxz and βzzz components. In the VB-2CT model, βxxz presents a maximum value for 2θ = 109.47°, whereas βxxz and μz have the same sign. On the other hand, βzzz decreases monotonically with θ, and its variations with the CT character follow a curve with two extrema like for one-dimensional D/A chromophores. The ab initio and semiempirical calculations as well as the VB-2CT model show that Λ-shaped molecules with large first hyperpolarizability and specific η = βxxz/βzzz can be designed in order to build phase-matchable second-harmonic generation crystals.

AB - The diagonal and off-diagonal tensor components of the first hyperpolarizability of a series of Λ-shaped molecules are compared by means of ab initio and semiempirical molecular orbital calculations. The calculated results are rationalized using expressions derived from a simple valence-bond charge-transfer model in which one ground and two excited state are described as a combination of one valence-bond (VB) and two charge-transfer (CT) states. In addition to the CT character, the angle (2θ) between the two donor (D)/acceptor (A) branches is a key parameter to determine the relative magnitudes between the βxxz and βzzz components. In the VB-2CT model, βxxz presents a maximum value for 2θ = 109.47°, whereas βxxz and μz have the same sign. On the other hand, βzzz decreases monotonically with θ, and its variations with the CT character follow a curve with two extrema like for one-dimensional D/A chromophores. The ab initio and semiempirical calculations as well as the VB-2CT model show that Λ-shaped molecules with large first hyperpolarizability and specific η = βxxz/βzzz can be designed in order to build phase-matchable second-harmonic generation crystals.

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