Banca de QUALIFICAÇÃO: MAYKOL CHRISTIAN DAMASCENO DE OLIVEIRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE: MAYKOL CHRISTIAN DAMASCENO DE OLIVEIRA
DATA: 09/09/2024
HORA: 14:00
LOCAL: Presencial - Auditório do Departamento de Fisica/UFPI
TÍTULO: Propriedades termo-óticas de pontos de carbono luminescentes produzidos a partir do mesocarpo de Orbignya speciosa (coco babaçu)
PALAVRAS-CHAVES: Carbon dots, Orbignya speciosa, Photoluminescence, Nonlinear Optics, Thermal Lens, Z-scan
PÁGINAS: 21
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
RESUMO:

Exploring materials with high nonlinearities derived from organic and biological sources has become a significant focus within the
scientific community. Among these materials, carbon dots (CDs) synthesized from biomass have emerged as promising candidates due to their
sustainable and cost-effective production methods. This study synthesized CDs from Orbignya speciosa (babassu coconut) biomass via a
hydrothermal route. UV-visible absorption and Infrared spectrum analysis revealed characteristic bands associated with the formation of dots and
the electronic transitions π-π* from aromatic C=C bonds in the CDs' core and n-π* transitions of surface carboxylate groups, photoluminescence
as a function of temperature and lifetime decay measurements show that the photoluminescence mechanisms in these materials due this
transitions comes from electronic indirect transitions from primary sources of the core and carbonyl boundings in the surface of the material,
additionally, to this the Dynamic Light Scattering (DLS) and Transmission Electronic Microscopy (TEM) give the structural properties of the dots,
amorphous and with a large size distribution with a mean size of (21±1) nm. Thermal lens spectroscopy (TLS) was employed to determine the
material's thermal diffusivity, reaching a maximum value of 2.03×10-7 m2/s as a function of dilution. The Z-scan technique under continuous wave
(CW) excitation at 532 nm investigated nonlinear optical properties, yielding a maximum thermal nonlinear refractive index (n2
(th)) value of
-3.77×10-7 cm2/W. Furthermore, the photothermal efficiency of the CDs was quantified at 532 nm, demonstrating a high absorption efficiency of
78.1%, suggesting their potential application in photothermal therapies. These findings contribute to understanding babassu coconut CDs'
thermo-optical behavior, highlighting their promise for various practical applications, particularly in biomedicine.

MEMBROS DA BANCA:
Presidente - 1780191 - FRANCISCO ERONI PAZ DOS SANTOS
Externo ao Programa - 2092477 - HANS ANDERSON GARCIA MEJIA
Externo à Instituição - RUBENS SILVA COSTA - IFPI
Externo ao Programa - 064.149.554-42 - SUZIETE BATISTA SOARES GUSMÃO - UFPI