Nonlinear Spectroscopy finished projects include:

1. Multi-photon functional optical sensing materials, IUT23-9

Project duration: 01.01.14 – 31.12.19

Principal Investigator: Prof. Aleksander Rebane

We will implement new experimental tools that will allow for the first time direct measurement of local electrostatic interactions in- and between molecules on nanometer-scale. Knowledge of how charges move inside molecules along with knowledge of the strength and direction of local electric fields is critical for understanding of key life processes. We take advantage of two-photon absorption (2PA) properties of specially-designed fluorescent chromophores, which consist in quantitative relationship between 2PA cross section and the amount of change of dipole moment that the chromophore undergoes upon optical excitation from ground- to excited electronic state, and where the last quantity serves as direct probe of the local static electric field strength. We will use these unique attributes of 2PA spectroscopy, in combination with NMR spectroscopy, to study light-induced charge-transfer and associated symmetry breaking in specially-designed organic and organo-metallic chromophores.

Link to ETIS here.

 

2. Femtosecond multi-photon spectroscopy of transition metal complexes, MOBJD69

Project duration: 01.03.17 – 28.02.19

Principal Investigator: Dr. Charlie Stark

Materials comprising complexes of transition metals with organic moieties possess unique properties that are instrumental for efficient light-induced charge separation and charge transport, and thus play increasingly important roles in the developing low-cost, versatile organic photovoltaic and light-emitting devices. This experimental project will study Ru(bpy)3 and Ru(phen)3 and related organometallic systems by determining the molecular electric dipole change in the metal to ligand charge transfer (MLCT) transition using a novel technique based on the quantitative determination of absolute femtosecond two-photon absorption cross section, and which facilitates determination of the dipole moment change with improved accuracy and fidelity compared to the traditional techniques such as Stark shift spectroscopy. This study contributes to improved materials and devices for the future sustainable energy production and lighting solutions.

Link to ETIS here.