Spectrum of the first molecular hyperpolarizability and multi-photon absorption in organic systems

• Grant number: 20/02979-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: June 01, 2020
• End date: December 22, 2020
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Cleber Renato Mendonça
• Grantee: Luis Miguel Gomes Abegão
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 18/11283-7 - Nonlinear photonics: spectroscopy and advanced processing of materials, AP.TEM

Abstract

The primary goal of the presented post-doctoral project is the implementation of an experimental system based on the hyper-Rayleigh scattering, by using a laser operating in the temporal regime of femtosecond and tunable wavelength in the range of from 500 nm to 2600 nm. With this apparatus, we intend to investigate the spectral behavior of the first molecular hyperpolarizability of several classes of materials, such as organic and organometallic compounds in solution, to identify the spectral region in which the materials exhibit the highest efficiencies regarding its molecular second harmonic generation. This study will provide relevant information about the relationship between molecular structure and the first hyperpolarizability, which is extremely pertinent to elucidate the proper mechanisms that could optimize the tailoring of organic compounds to achieve the higher efficiency of the optical nonlinear response. Also, in this project, the same experimental apparatus could be used, with some minor modifications, for the study of multiphoton excitation. It is also our intention to simulate all the experimental results with Quantum Chemical calculations using the time-dependent density functional theory implemented in Gaussian software, which will give us a better understanding of the interpretation of the experimental results. (AU)