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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. April 2004, Volume 3, Number 4, 209-221 |
Modifications in the Maximal Intensity of Four-Wave Mixing Signal
under the Changes of Vibronic Coupling Conditions
José Luis Paz, Teresa Cusati, and Antonio J. Hernández
Internet Electron. J. Mol. Des. 2004, 3, 209-221
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Abstract:
The spectroscopic analysis of the behavior of the nonlinear signal
response of systems including electronic levels is described by
the coupling parameters of crossed harmonic potential curves.
Changes in the Four-Wave Mixing (FWM) signal intensity are
originated by the modifications of the dipole moments in the new
coupled basis due to variation of the parameters V0 (energetic
difference between the minima), v (coupling parameter) and δ
(strength constant) corresponding to the crossed states involved.
The permanent dipole moments of the states in the uncoupled
basis have been included and the Rotating-Wave Approximation
is neglected in order to observe the processes out of the
resonance region. The calculation method is based in the
Liouville-von Neumann formalism for the density matrix, where
the Conventional Optical Bloch Equations are solved in the
Fourier space to obtain the density matrix elements associated
with the Macroscopic Polarization responsible of the FWM
signal. Variation in the coupling parameters generates
modifications in the dipole moments of the coupled states. These
modifications induce changes in the intensity values of the FWM
signal, including the nullity of the dipole moments producing the
nullity of the nonlinear signal. Mathematical expressions are
obtained to interprete these results. Changes in the characteristic
coupling parameters induce modifications on the crossed
potential curves, and consequently, on the nonlinear response
and intensity.
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