Quantum Chemistry Investigations on Nonlinear Optical Materials
: from Reference to Complex Systems

Student thesis: Doc typesDoctor of Sciences

Abstract

The interplay between light and matter gives rise to several nonlinear optical (NLO) phenomena. This thesis aims at describing and understanding, using quantum chemistry, the NLO properties of molecules. In particular, it focuses on their second (SHS, β_SHS) and third (THS, γ_THS) harmonic scattering responses. The goal is to provide insights and to help towards the design of new materials, in a multidisciplinary framework combining theory and experiment. The first part is dedicated to the accurate description of (gas phase) molecular responses of reference molecules, crucial for experimental measurements. So, the first quantum chemical investigation on γ_THS is reported. Then, using a homemade implementation of finite-field differentiation techniques, the impact of vibrational contributions has been addressed for the water molecule. The second part focuses on molecules of increasing complexity, displaying remarkable second-order NLO responses. On the one hand, NLO switches have been explored, with a focus on the structure-β_SHS relationships. Two types of compounds have been considered: i) octupolar molecules with 6 ruthenium(II) centers that can be oxidized and ii) multi-state compounds, involving two or three benzazolooxazolidine units, leading up to 4 or 8 different states. On the other hand, a new methodology to study the NLO responses of fluorescent proteins, biotags of interest in second-harmonic imaging microscopy, has been developed.
Date of Award7 Oct 2021
Original languageEnglish
Awarding Institution
  • University of Namur
SponsorsUniversité de Namur
SupervisorBenoit CHAMPAGNE (Supervisor), Olivier DEPARIS (President), Marc DE WERGIFOSSE (Jury), Vincent Liegeois (Jury), Daniel Vercauteren (Jury), Frédéric Castet (Jury) & Lionel Sanguinet (Jury)

Keywords

  • Quantum Chemistry
  • nonlinear optic
  • molecular switches
  • Quantum chemistry method
  • harmonic generation

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