TY - JOUR
T1 - Characterization of Cuban and Brazilian natural zeolites by photoacoustic spectroscopy and electron paramagnetic resonance
AU - Lara-Bernal, Arlem
AU - Da Silva, Marcelo G.
AU - Mota, Leonardo
AU - Marín, Ernesto
AU - Cordeiro, Thallis C.
AU - Da Silva, Edson C.
AU - Viana, Daniel A.
AU - Vargas, Helion
AU - Polidoro, José Carlos
AU - Mello-Monte, Marisa Bezerra De
N1 - Publisher Copyright:
© 2022, Academia Brasileira de Ciencias. All rights reserved.
PY - 2022
Y1 - 2022
N2 - This report describes the photoacoustic and electron paramagnetic resonance investigations of Brazilian and Cuban zeolites. Photoacoustic optical absorption measurements indicate the presence of iron (Fe3+) ions with their respective transition bands for both zeolites. Two species of manganese (Mn2+ and Mn3+) were identified in the Cuban sample and the electronic transitions assigned. Iron and manganese ions were confirmed through nonradiative relaxation (t) and characteristic diffusion (-cp) times evaluation, whose values were found to be tBRA = 5.40 ms, tcub = 4.60 ms, cpBRA = 387 ^s and cpCUB = 305 ^s. Crystal field (Dq-BRA/Dq-CUB = 1048 cm-1/945 cm-1) plus Racah (B-bra/B-cub = 457 cm-1/8l3 cm-1 and C-bra/C-cub = 3655 cm-1/2496 cm-1) parameters were assessed as well. Paramagnetic resonance corroborated Fe3+ ions present in the Brazilian zeolite occupying sites showing axial and/or rhombic symmetry distortions. For the Cuban sample, results reveal the characteristic hyperfine sextet lines of Mn2+ overlapping the Fe3+ line. Values of Lande factor and isotropic hyperfine splitting constant were found to be 2.0 and 9.7 mT, respectively. This tells us that the Mn2+ lies in octahedral symmetry probably replacing calcium ions and point towards an ionic bonding character of the Mn2+ and its surroundings.
AB - This report describes the photoacoustic and electron paramagnetic resonance investigations of Brazilian and Cuban zeolites. Photoacoustic optical absorption measurements indicate the presence of iron (Fe3+) ions with their respective transition bands for both zeolites. Two species of manganese (Mn2+ and Mn3+) were identified in the Cuban sample and the electronic transitions assigned. Iron and manganese ions were confirmed through nonradiative relaxation (t) and characteristic diffusion (-cp) times evaluation, whose values were found to be tBRA = 5.40 ms, tcub = 4.60 ms, cpBRA = 387 ^s and cpCUB = 305 ^s. Crystal field (Dq-BRA/Dq-CUB = 1048 cm-1/945 cm-1) plus Racah (B-bra/B-cub = 457 cm-1/8l3 cm-1 and C-bra/C-cub = 3655 cm-1/2496 cm-1) parameters were assessed as well. Paramagnetic resonance corroborated Fe3+ ions present in the Brazilian zeolite occupying sites showing axial and/or rhombic symmetry distortions. For the Cuban sample, results reveal the characteristic hyperfine sextet lines of Mn2+ overlapping the Fe3+ line. Values of Lande factor and isotropic hyperfine splitting constant were found to be 2.0 and 9.7 mT, respectively. This tells us that the Mn2+ lies in octahedral symmetry probably replacing calcium ions and point towards an ionic bonding character of the Mn2+ and its surroundings.
KW - Characteristic diffusion time
KW - Natural zeolites
KW - Nonradiative relaxation time
KW - Phase resolved method
KW - Racah parameters
UR - http://www.scopus.com/inward/record.url?scp=85124056443&partnerID=8YFLogxK
U2 - 10.1590/0001-3765202120200512
DO - 10.1590/0001-3765202120200512
M3 - Artículo
C2 - 35107514
AN - SCOPUS:85124056443
SN - 0001-3765
VL - 94
JO - Anais da Academia Brasileira de Ciencias
JF - Anais da Academia Brasileira de Ciencias
IS - 1
M1 - e20200512
ER -