Events

Seminar "Coherence-Correlations-Complexity", Dept. of Theoretical Physics, Wrocław University of Technology

On effective orientational ordering of octupolar molecules: challenges and recent results

Michał Jarema

Katedra Fizyki Teoretycznej WPPT PWr

The first generation of molecular engineering for non-linear optics has concentrated on polar conjugated molecules. The broader template of multipolar molecules was first proposed by Zyss [1]. A conceptual frame for a study of practical implementations of general electric field induced multipoling configurations which generalize the dipolar orientation schemes (EFISH)  to multipolar orientation schemes (MEFISH) was recently formulated using statistical physics approach [2]. This framework was used to study the conditions for an effective electric field poling of so-called “Y” shaped flat octupolar molecules in two dimensions [3-5]. The octupoling criteria were highly demanding and required sub-Helium temperatures. In this paper we present recent results oriented onto a softening of poling conditions, obtained using analytical and numerical methods, in particular Mean Field Approximation, Quantum Chemistry and Monte Carlo simulations. Both 2-d and 3-d octupolar molecules are studied in two and three dimensions. The main point of interest is the stability of the ground state non-centrosymmetric configurations. We have found that the intermolecular interactions (apart from the octupoling electric field) play an important role. We present some specific poling schemes which might be effective at Nitrogen temperatures.    

1. J. Zyss,  Octupolar Organic Systems in Quadratic Nonlinear Optics: Molecules and Materials, Nonlinear Optics 1, 3 (1991).
2. J. Zyss, From Octupoles to Octupoling and from Electric Field Induced Second-Harmonic (EFISH) to Multipolar Field Induced Second-Harmonic (MEFISH), Nonl. Opt. Quant. Opt. 43, 97 (2012).
3. A.C. Mitus, G. Pawlik, and J. Zyss, On Effective Electric Field Nano-Octupoling in Two Dimensions, J. Chem. Phys. 135, 024110 (2011).
4. M. Jarema, A.C. Mitus, and J. Zyss, Poling in Two Dimensions by a Purely Octupolar Electrostatic Potential: Homogeneity of the Ground State, Acta Phys. Pol. B 43, 1017 (2012).
5. A.C. Mitus, M. Jarema, G. Pawlik, and J. Zyss, Nano–Octupoling in Two Dimensions by a Purely Octupolar Electrostatic Potential, Nonl. Opt. Quant. Opt. 43, 133 (2012).