Faculty_Mabrouk_Zouari – MUST University

Pr. Mabrouk Zouari

mabrouk.zouari@mustuniversity.tn

00216 71 180 108

Box : 118

Biography

Mabrouk ZOUARI holds a Master in Physics, a PhD in Optical Signal Processing, a PhD in Physics and Mechanics “modeling of a high-power laser source. Application to the cases of laser machining”, from Strasbourg University and a State Doctorate in Physics (HDR: Habilitation of direction of research), “Study of ultrafast processes in molecular adsorbates by five-wave mixing spectroscopy”, from the Faculty of Science of the El Manar University. He worked as a professor of physics at the University of Sfax and then at the University of Carthage, Tunisia.

Research

Current Research: Polarization effects on cross-peaks induced by intermolecular vibrational energy transfer in two-dimensional infrared spectroscopy (2DIR). I am currently interested to describe analytically the role of the polarization effects acting on the cross peaks associated to coherence transfer processes. A proper account of these polarization effects is essential to interpret and analyze quantitatively the efficiency of the vibrational energy transfer occurring between different molecules. When the energy transfer process takes place between dark combination states of low frequency modes pertaining to different molecules, the appearance of the cross-peaks by a two-dimensional spectroscopy experiment is the best way to get information about the structure and the underlying dynamics taking place between these combination states and optically active states of the molecule. In these bimolecular processes, the polarization effects cannot be anymore introduced as a simple additional dephasing and a complete description and modeling of the polarization effects need to be introduced.

Teaching

Electricity, Optics, Mechanics, Electromagnetism, Electromagnetic, waves propagation, Restraint relativity, Thermodynamics, Heat transfer, Introduction to quantum mechanics. Laser Physics, Laser and applications. signal processing

Publications

Within the framework of the preparation of the doctoral thesis of the Strasbourg University my research works concerned the interaction radiation-matter and the laser application in industry. This subject aroused a lot of attention for its scientific and technological importance. The lasers which I used are: CO 2 laser and YAG the power of which can achieve 1.5kW.
Afterward I directed my researches to the nonlinear methods spectroscopic to study the ultrafast dynamic processes in the molecular adsorbates.
We first developed a theoretical description of the ultrafast dynamical processes taking place in the molecular adsorbates. An extensive analytical theory of sum-frequency generation with infrared pump and infrared-visible probe is presented. This description is done in terms of five-wave mixing for both steady-state and time-resolved experiments. It has been shown that the fourth-order induced polarization at the sum-frequency signal can be expressed as sum of different components which are induced by the different field-molecule interactions.
Numerical simulations have been performed on the C-H stretched mode on the hydrogen- terminated H/C(III)(1×1) surface to evaluate the dephasing constants. Later, by introducing a time delayed structure of the probe pulses, we demonstrate the ability of these experiments to analyze the various dephasing processes in the excited configurations. In the last part of this work the contributions of the substrate electric field to the molecular optical nonlinearities have been evaluated. In the limiting case of an homogeneous electrostatic field, besides the contributions associated to the induced dipole moments, we have additional contributions which only exist if the adsorbed molecule has permanent dipole moments. For the more general inhomogeneous electrostatic field case, while the main observations remain valid, the Franck-Condon factors are modified by the molecular structure changes induced by the electrostatic field. In addition, we have a strong redistribution of the vibronic couplings resulting from analytical Q-dependence of the partial charge distribution which is a signature of the field inhomogeneities.