The work performed and results obtained in QuESt are the following:
1. Development of the theoretical framework to describe the collective coupling of molecules to an optical cavity mode that allowed the calculation of the energy structure and dynamics of coupled systems and how they relate to the observed non-linear response in optical experiments such as transient absorption. This was specifically applied to an ensemble of strongly coupled molecules (4CzIPN) (work published on J. Phys. Chem. Lett. 2020). A general perspective that discussed the possibilities enabled by placing many molecules in optical cavities that interact with the same mode of the electromagnetic field, with a focus on the collective behavior and delocalization of polaritons, similar to molecular excitons, and the ultrafast photophysics that can be explored by non-linear spectroscopies was produced and published in J. Phys. Chem. Lett in 2021.
2. Theoretical interpretation of the charge transfer mechanism in materials relevant to organic photovoltaics investigated by pump-push-probe. This work provides new insights into the microscopic origin that allows efficient charge separation in organic materials for OPVs. Work is ready for submission for publication in peer reviewed journal.
3. Investigation on the entanglement properties of molecular polaritons. In this direction, a proposal to measure exciton entanglement (here understood as delocalization) through linear spectroscopy was carried out (published in PRA in 2021) and the extension to polaritons is in progress.
4. Complementary to the scientific activities strictly related to the core of the project, and within the broader field of utilizing quantum phenomena to modify function in molecular systems, investigations on excited state intramolecular proton transfer (ESIPT) were carried out. In this context, the fellow supervised a PhD student working on the theoretical aspects of the project to develop an open quantum systems approach to treat ESIPT and analyze the role of quantum coherence. In particular, in a combined experimental and theoretical work, it was proposed that quantum interference may explain unconventional isotope effects in two-site excited state intramolecular proton transfer revealed by experiments performed in the group of Prof. Scholes (Princeton). This work was published in PNAS in 2021.
5. Also in the context of mentoring a PhD student (as in #4), studies of intramolecular proton transfer in single-site molecules and the associated ultrafast optical response were carried out. The aim was to clarify what is the microscopic mechanism behind the ultrafast ESIPT mechanism which is a matter still under debate. This work was published in 2022 in ACS Physical Chemistry Au.
In addition to the dissemination of the work in scientific journals, outreach activities toward the general public were carried out:
[1] Article in local newspaper Il Piccolo, highlighted on SISSA social media
https://www.facebook.com/SISSAschool/posts/an-article-dedicated-to-physicist-francesca-fassioli-olsen-was-published-in-il-p/1646262625419306/(opens in new window)[2] 'Lightweight, bendy, cheaper' – the promise of organic solar panels', article in Horizon Magazine
[3] 'Le donne nella città della scienza', participation in exhibition on female scientists in the city of Trieste
