Decoherence and Dephasing of Vibronic Excitons /

In organic molecular assemblies, photo-induced energy and charge transfer is accompanied by significant intramolecular nuclear rearrangements. Therefore, optical excitations are described as quasiparticles excitons. Coupling to vibrational degrees of freedom is often a dominating factor in the description of the exciton dynamics, therefore the vibronic exciton theory has to be used. In this thesis, the significance of dephasing and decoherence of vibronic excitons in molecular systems is investigated and the signatures of electronic-vibrational interaction in the two-dimensional electronic spectra are analyzed with the focus on evolution of molecular excitation and quantum coherences. It is shown, that (i) quantum coherences of electronic, vibrational or mixed nature can be discriminated through the analysis of coherent oscillations in the two-dimensional spectrum, (ii) the effect of static energetic disorder on the coherences depends on the nature of the states involved in the quantum superposition, (iii) for vibronically-coupled systems, the lifetime of excitonic coherences are determined by the coupling to discrete modes of intramolecular vibrations and by proximity of the system parameters to an excitonic--vibrational resonance, (iv) the electronic and vibronic energy level structure of the six-porphyrin nanoring is determined by the non-trivial combined effect of energetic disorder, vibronic coupling and small geometric deformations of the nanoring.

Grantor dc:publisher

Institutional Repository of Vilnius University

Year dc:date

2015

Author dc:creator

• Butkus, Vytautas,

Contributors dc:contributor

• Valkūnas, Leonas

• laser spectroscopy ; molecular vibrations ; excitons ; response function theory ; porphyrin aggregates

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Repository record dc:identifier

https://repository.vu.lt/VU:ELABAETD11750060&prefLang=en_US

OAI identifier oai:identifier

oai:vu.lt:elaba:11750060