THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:

Chemistry in optical microcavities: Spectral fluctuations and energy transport

Prof. Dr. Raphael Ribeiro

Department of Chemistry, Emory University – Atlanta, USA

Abstract:

Optical cavities and metallic nanoparticles confine electromagnetic fields and enable new pathways to control physicochemical processes via strong light-matter interactions. In fact, recent experiments have shown that photonic and plasmonic materials may induce significant and sometimes unexpected changes to physical properties and reactivity of molecular systems. In this talk, I will introduce and present the key results of our recent theoretical investigations on the effects of collective radiation-matter interactions on transport and spectral properties of disordered molecular ensembles hosted by a resonant 1D optical cavity (photonic wire). The main implications of our findings to future theoretical and experimental research will be discussed. I will show that widely employed minimal theoretical models fail to adequately describe photonic effects on the local properties of chemical systems and explain strategies to maximize the influence of optical cavities on molecular materials informed by our simulations.

Date: November 19, 2021 – (friday) – Time: 10:15 a.m.

link to access the youtube channel: https://youtu.be/8nV3QDFmhB8

THE PHYSCIS GRADUATE PROGRAM invites everyone to the seminar:

What Hampers Electron Transport in Organic Crystals? A Close Look at Band-like Transport in N-type Organic Semiconductors

Prof. Dr. Emanuele Orgiu

Institut National de la Recherche Scientifique – INRS, Québec – Canada

Abstract:

Charge transport in organic semiconductors is notoriously sensitive to the presence of disorder, both intrinsic and extrinsic, especially for n-type materials. Intrinsic dynamic disorder stems from large thermal fluctuations both in intermolecular transfer integrals and (molecular) site energies in weakly interacting van der Waals solids and sources transient localization of the charge carriers. The molecular vibrations that drive transient localization typically operate at low-frequency (< a-few-hundred cm-1), which makes it difficult to assess them experimentally. Hitherto, this has prevented the identification of clear molecular design rules to control and reduce dynamic disorder. In addition, the disorder can also be extrinsic, being controlled by the chemical and physical “coupling” of the π-conjugated core to the gate dielectric. During the Colloquium, I will present a comprehensive study of charge transport in two closely related n-type molecular organic semiconductors using a combination of temperature-dependent inelastic neutron scattering and photoelectron spectroscopy corroborated by electrical measurements, theory and simulations. By doing so, unambiguous evidence is provided that ad hoc molecular design enables to free the electron charge carriers from both intrinsic and extrinsic disorder to ultimately reach band-like electron transport.

Date: November 12, 2021 – (friday) – Time: 10:15 a.m.

link to access the youtube channel: https://youtu.be/TE3LD1NKi4c

THE PHYSCIS GRADUATE PROGRAM invites everyone to the seminar:

Gauge invariant quantum thermodynamics: consequences for the first law

Prof. Dr. Lucas Chibebe Céleri

Instituto de Física – UFG

Abstract:

Universality of classical thermodynamics rests on the central limit theorem, due to which measurements of thermal fluctuations are unable to reveal detailed information regarding the microscopic structure of a macroscopic body. When small systems are considered and fluctuations become important, thermodynamic quantities can be understood in the context of classical stochastic mechanics. A fundamental assumption behind thermodynamics is therefore that of coarse-graining, which stems from a substantial lack of control over all degrees of freedom. However, when quantum systems are concerned, one claims a high level of control. As a consequence, information theory plays a major role in the identification of thermodynamic functions. Here, drawing from the concept of gauge symmetry, essential in all modern physical theories, a new, intermediate, route is put forward. Working within the realm of quantum thermodynamics, a physically motivated gauge transformation, which encodes a gentle variant of coarse-graining behind thermodynamics, is explicitly constructed . As a consequence, quantum work and heat are reinterpreted, as well as the role of quantum coherence.

Date: November 5, 2021 – (friday) – Time: 10:15 a.m.

link to access the youtube channel: https://youtu.be/ieeh_LtXBgI

O Programa de Pós-Graduação em Física da UFSC torna público os editais do processo seletivo para os cursos de mestrado e doutorado para ingresso no semestre 2022/1.

As inscrições ocorrerão no período de 1 a 30 de novembro de 2021. O PPGFSC utiliza a nota do Exame Unificado de Pós-Graduações em Física – EUF para ingresso nos cursos de mestrado de doutorado.

Click aqui e acesse o site do processo seletivo do PPGFSC/UFSC.

Below is the link to access the result of the PPGFSC / UFSC Simplified Selection Process for admission to master and doctoral courses in the semester 2021/2:

Results

The candidates who receive a scholarship will be informed after the Scholarship Committee meeting.

THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar

Virtual-Slit Focusing in a Cycloidal Mass Spectrometer – A Proof of Concept

Dr. Rafael Bento Serpa

Postdoctoral Associate | Duke University Nanomaterials and Thin Films Lab

Abstract:

This work demonstrates a novel approach to mass spectrometry using the “virtual-slit” created by the small, spatial volume from which ions are generated by localized ionization techniques (e.g., laser ionization of particles and surfaces, and spark ionization). That is, the volume in which the ions are generated creates a localized source of ions in much the same way as a slit that allows only ions from a specific cross-sectional area to pass. As demonstrated in this work, the unique perfect focusing properties of a cycloidal mass analyzer can enable the localized ionization volume to function as a virtual slit. In this manuscript, we provide a proof-of-concept (POC) demonstration of a virtual-slit cycloidal mass spectrometer (VS-CyMaS) consisting of a cycloidal mass analyzer, a laser ionization source, and an ion array detector. The laser is used to ionize either bulk or thin-film samples of Cu, Ti, Ni, and Cr. Results indicate that the width of the peaks at the detector is the same as the laser spot size, validating the concept of virtual-slit focusing. Furthermore, the material ablated with each laser pulse for Ti and Cu is estimated at 60 and 140 fg, respectively, indicating that a very low detection limit is possible given the ability of the cycloidal mass analyzer to collect ions generated by laser ionization that have wide energy and angular dispersions.

Date: October 29, 2021 – (friday) – Time: 10:15 a.m.

link to access the youtube channel: https://youtu.be/t75RNYAdy1s

The Graduate Program in Physics of the Federal University of Santa Catarina – UFSC – announces the list of the approved applications for the Simplified Admission Process entrance at the semester 2021/2.

Click here to see the list of registered candidates and their respective situation in the admission process.

Period for appealing the application decision: from October 21, 2021, at 0 AM, to October 26, 2021, at 11:59 pm.

Defense of Doctoral Thesis

Everton Botan

IDENTIFICATION OF VARIABLE STARS IN THE VVV SURVEY AND INVESTIGATION OF STRUCTURES IN THE GALACTIC BULG

Defense Committee:

Prof. Dr. Roberto Kalbusch Saito – (president) – (UFSC/FSC)

Prof. Dr. Jacques Raymond Daniel Lepine – (external member) – IAG/USP

Prof. Dr. Helio Jaques Rocha-Pinto – (external member) –  Observatório do Valongo – UFRJ

Prof. Dr. Daniel Ruschel Dutra – (membro titular) – UFSC/FSC

Prof. Dr. Antônio Nemer Kanaan Neto – (201701791) – UFSC/FSC

Date: October 29, 2021 – friday – Times: 9:30 am – Place: videoconference

Virtual room access link: https://meet.google.com/dof-hsws-ezf

THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:

Aberration and Doppler effect on the CMB: kinematical and intrinsic contributions

Dr. Omar Roldán

Pós-doutorando – UFRJ

Abstract:

The aberration and Doppler coupling effects of the Cosmic Microwave Background (CMB) were measured by the Planck satellite. The most straightforward interpretation leads to a direct detection of our peculiar velocity, consistent with the measurement of the well-known dipole. We show however, that in some cases a primordial dipolar potential can also produce such effects. But in addition it produces other signatures due to integrated terms which we will discuss in some detail. We also discuss how aberration measurements can be used to constraint some models which introduce super-horizon perturbations to explain the hemispherical asymmetry. This work has also been used to infer the Intrinsic Dipole. Finally we also discuss about CMB anisotropies at all orders and the non-linear Sachs-Wolfe formula.

Date: October 22, 2021 – (friday) – Time: 10:15 a.m.

link to access the youtube channel: https://youtu.be/sqea8-jX35Q

THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:

Transporte eletrônico em nanoestruturas com quiralidade

Prof. Dr. Luis Guilherme de Carvalho Rego

Departamento de Física, UFSC

Abstract:

A quiralidade geométrica é facilmente percebida em uma figura cuja imagem no espelho não pode ser superposta com ela mesma. No entanto, o conceito de quiralidade dinâmica tem mais relevância, pois conecta o mundo observável com propriedades fundamentais da natureza. Neste trabalho (DOI:10.1021/acs.nanolett.1c02636) investigamos a propagação de elétrons em nanofios helicoidais e verificamos que a interação entre momento angular de spin e a quiralidade do nanofio, interligados pela interação spin-órbita, gera uma assimetria na direção de propagação das partículas. O efeito é induzido pela quebra de paridade, causada pela quiralidade da estrutura molecular do fio. Para realizar este estudo utilizamos um modelo microscópico que leva em consideração a interação spin-órbita no material. Os cálculos são aplicados a um novo material, uma cadeia dupla hélice totalmente inorgânica feita do material SnIP, que é um semicondutor com bandgap de ~ 1,9 eV. Por fim, consideramos a relação deste efeito com fenômenos associados, dentre eles: polarização de spin induzida por quiralidade (efeito CISS), propagação de carga em nanotubos de carbono, e atividade óptica em materiais quirais e metamateriais.

Date: October 15, 2021 – (friday) – Time: 10:15 a.m.

link to access the youtube channel: https://youtu.be/3vvnv2iGHVU