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
pf
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}, doi = {10.1080/00268976.2010.493898} } |