Nonlinear Spectroscopy

Nonlinear Spectroscopy research head is Prof. Aleksander Rebane

1. Measurement of electric fields in DNA, PSG317

Project duration: 01.03.19 – 31.12.22

Principal Investigator: Dr. Charles Stark

Deoxyribonucleic Acid (DNA) is a complex biomolecule that serves as long-term information storage in all living organisms. The remarkable longevity of DNA stems from the chemical stability of the individual nucleosides, but also from many interactions between sequential nucleosides as well as larger structures that pack and protect this sequence. Although these large-scale effects have been observed, the affects they have on the stability of DNA is not well understood, particularly in terms of the electric forces that hold the extended structure together, which act over scales of approximately 1-100 nanometers. Our lab has developed “Molecular Voltmeter” probes capable of measuring nanoscale electric fields using the nonlinear optical technique known as two-photon absorption spectroscopy. These probes can be inserted into DNA, and we plan to use them to measure the electric field between nucleosides. The Masters student will be handling DNA samples, preparing buffer solutions, assisting in the process of intercalating probes, and learning the techniques of two-photon absorption spectroscopy. Along with research tasks which they can use for their Masters thesis, they will have the opportunity to attend international conferences and be involved in publishing results in scientific journals. This research has a stipend of 300.00 EUR / month for at most 2 years.

Thesis topics for students

Masters Student needed in researching electric fields in DNA

2. 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.

Our high quality work is presented also in Multihoton Spectra database 

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