Banca de DEFESA: MATEUS AUGUSTO MARTINS DE PAIVA
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.DISCENTE : MATEUS AUGUSTO MARTINS DE PAIVA
DATA : 15/08/2019
HORA: 14:00
LOCAL: Campus VI
TÍTULO:
Ab initio study on the formation and destruction of the SiS molecule and its astrochemical relevance
PALAVRAS-CHAVES:
OSiS, SiS, SiO, H2S, HS, Astrochemistry, MRCI, Interstellar.
PÁGINAS: 54
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Química Teórica
RESUMO:
Astrochemistry is still an interdisciplinary vanguard science. The means and framework for its
development did not appear until the late twentieth century. For this reason, there are still many open
problems to be solved and studied. Astrochemistry has as main objective to study the chemistry of the
cosmic environment, proposing reaction mechanism and explanations for the formation of certain
molecules, experimentally or not.
Several astronomers have already made observations of the isolated OSi and SiS
molecules in certain space regions, but no observations have been made for the OSiS
molecule, even though there is evidence that it is a link between OSi and SiS. The OSi
molecule has already been well studied and its origin of formation is well understood.
However the SiS received less attention and its formation in the interstellar environment is
still subject of debate.
The aim of this work is to propose a possible reaction path for the relationship of these
molecules, through ab initio calculations. By studying the potential energy surface of the OSiS
molecule, it has been discovered that the SiS molecule is easily converted to OSi, in
collisions with oxygen, but the conversion of OSi to SiS does not occur. It has also been
found that the reaction of OSi + S leads to the formation of the stable molecule OSiS in its
singlet state through a crossing region of singlet and triplet states, in addition it is envisaged
that other isomers can also be formed by this route, such as cyclic OSiS and SOSi.
It has been found that the SiS molecule can be formed by reactions between atomic
silicon with hydrosulphide molecule (HS) and hydrogen sulfide (H 2 S). In the reaction with HS
the SiS molecule is easily formed, but with H 2 S the reaction happens with exchange of
spin states. Both reactions are exothermic. The reaction paths for several other molecules
and isomers that are related to silicon, sulfur and hydrogen has also been proposed.
MEMBROS DA BANCA:
Presidente - BRENO RODRIGUES LAMAGHERE GALVAO
Externo ao Programa - LUIS ARGEL POVEDA CALVINO
Externo à Instituição - MATEUS XAVIER SILVA - UFMG
Externo à Instituição - VINICIUS CÂNDIDO MOTA - UFES