(Português) Programa de Pós-Graduação em Física da UFSC, Florianópolis

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O Programa de Pós-Graduação em Física convida para o colóquio:

«How to make a TV using just blue organic light emitting diodes»*

Prof. Andrew P. Monkman, Department of Physics, University of Durham, UK

*Evento de presença obrigatória da disciplina seminários

Resumo:
AMOLED TV’s and computer screens are pretty becoming common place. The challenge for scientists and industry is now to make them cheaper, with very high production yields and high energy efficiency. Surprisingly, one way to do this is use only blue emitting pixels! In this seminar I will explain why this is and the problems it creates with designing appropriate materials and pixel architectures. I will then show how my research group have used dedicated ultrafast time resolved spectroscopy and OLED device characterization to get us closer to solving the problems so that this concept can become a reality.

Data: 17 de abril de 2026 (sexta-feira) – Horário: 10h15min
Local: Auditório Faruk Nome, Departamento de Química – UFSC

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O Programa de Pós-Graduação em Física convida para o colóquio:

«The Glass Transition and Delayed Luminescence in Columnar Mesophases»*
Dr. Harald Bock, Centre de Recherche Paul Pascal, CNRS & Univ. Bordeaux, France

*Evento de reposição da disciplina seminários

Resumo:
Columnar liquid crystals, made of stacks of aromatic disk-shaped molecules, are alignable viscous fluids that allow anisotropic migration of charges and of excited states. They may go through a glass transition, yielding an anisotropic solid with improved robustness. The proximity of parallel chromophores also favors radiative triplet-triplet recombination to give delayed fluorescence. I will discuss our recent findings in this field.

Data: 14 de abril de 2026 (terça-feira) – Horário: 10h
Local: Auditório Faruk Nome, Departamento de Química – UFSC

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O Programa de Pós-Graduação em Física convida para o colóquio:

«Mapping the shutting down of star formation from the local universe to the first galaxies»*

Dr Hin Leung, Royal Observatory of Edinburgh, UK

*Evento de presença obrigatória da disciplina seminários

Resumo:
From large galaxy surveys in the local universe, we find galaxies that are star-forming and galaxies that have mostly stopped forming stars. Those that are no longer forming stars must have at some point quenched their ongoing star formation and evolved passively to achieve the current “red and dead” state. However, the precise physical drivers of this quenching process are still highly debated.

In this talk, I will show results from studying recently quenched galaxies in the local universe. We found that a majority of these galaxies became significantly more metal-rich over a short period, indicating that whatever led to their quenching must also inflate their metal abundance without significant dilution from inflowing metal-poor gas. From looking at spatially resolved information collected in spectroscopic surveys, and applying a novel Hierarchical Bayesian modelling approach to include radial gradients of regional properties, we found evidence that their recent quenching could be caused by mergers with neighbouring galaxies.

Moving to more distant galaxies, from a sample of 14 massive quenched galaxies observed by JWST within 2 billion years after the Big Bang, we found strong evidence for “downsizing” to already be in place at early times. This means more massive galaxies formed earlier than less massive galaxies. Some of these most massive cases might be “cosmology-breaking”, where they are more massive than what a galaxy could reach in the same time predicted by lambda CDM, even with 100% baryonic assembly efficiency. From a broad search for all early and massive quenched galaxies, we report that almost all current cosmological simulations are under-predicting the number densities of these objects by ~2x. These suggest that substantial revisions to our models of early galaxy formation and quenching are needed.

Data: 10 de abril de 2026 (sexta-feira) – Horário: 10h15min
Link de acesso a sala virtual: https://conferenciaweb.rnp.br/ufsc/ppgfsc