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Molecular QED of coherent and incoherent sum-frequency and second-harmonic generation in chiral liquids in the presence of a static electric field

2010

Article

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Coherent second-order nonlinear optical processes are symmetry forbidden in centrosymmetric environments in the electric-dipole approximation. In liquids that contain chiral molecules, however, and which therefore lack mirror image symmetry, coherent sum-frequency generation is possible, whereas second-harmonic generation remains forbidden. Here we apply the theory of molecular quantum electrodynamics to the calculation of the matrix element, transition rate, and integrated signal intensity for sum-frequency and second-harmonic generation taking place in a chiral liquid in the presence and absence of a static electric field, to examine which coherent and incoherent processes exist in the electric-dipole approximation in liquids. Third- and fourth-order time-dependent perturbation theory is employed in combination with single-sided Feynman diagrams to evaluate two contributions arising from static field-free and field-induced processes. It is found that, in addition to the coherent term, an incoherent process exists for sum-frequency generation in liquids. Surprisingly, in the case of dc-field-induced second-harmonic generation, the incoherent contribution is found to always vanish for isotropic chiral liquids even though hyper-Rayleigh second-harmonic generation and electric-field-induced second-harmonic generation are both independently symmetry allowed in any liquid.

Author(s): Fischer, Peer and Salam, A.
Journal: MOLECULAR PHYSICS
Volume: 108
Number (issue): 14
Pages: 1857-1868
Year: 2010

Department(s): Micro, Nano, and Molecular Systems
Bibtex Type: Article (article)

DOI: 10.1080/00268976.2010.493898

BibTex

@article{ISI:000280153100005,
  title = {Molecular QED of coherent and incoherent sum-frequency and second-harmonic generation in chiral liquids in the presence of a static electric field},
  author = {Fischer, Peer and Salam, A.},
  journal = {MOLECULAR PHYSICS},
  volume = {108},
  number = {14},
  pages = {1857-1868},
  year = {2010}
}