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M. Cortez-Valadez,L. P. Ramírez-Rodríguez,J.-G. Bocarando-Chacon,M. FLORES-ACOSTA,S. VELUMANI,R. Ramírez-Bon 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.7
"Cadmium colloidal crystalline nanoparticles were obtained by a simple green synthesis method employing the plant extract of Opuntia ficus-indica. The plant extract reduces the Cd ions and stabilizes the size of cadmium colloidal particles at the nanometric level. The size and morphology of agglomerates of nanoparticles of about 100 nm were analyzed by field-emission scanning electron microscopy (FESEM). The size, shape and crystalline structure of the Cd nanoparticles were determined from TEM analysis. The results show that Cd nanoparticles with hexagonal crystalline structure and average size 2–3 nm were obtained by this green synthesis method. The optical absorption spectrum of the colloidal solution containing the cadmium nanoparticles displays an optical absorption band centered at 236 nm, which was attributed to the plasmon resonance of the Cd colloidal nanoparticles. Mie theory for colloidal systems was applied to reproduce theoretically the plasmon resonance absorption data of the Cd colloidal nanoparticles. Furthermore, the Raman spectrum of powder from dried samples after reduction of cadmium ions, displays a low wavenumber vibration mode centered at 114 cm-1, assigned to the Cd nanoparticles. Density functional theory (DFT) calculations at local spin density approximation (LSDA) level were performed to determine the structure and vibrational properties of small clusters of cadmium consisting of 3–10 atoms. Radial breathing modes with frequencies between 90 cm-1 and 120 cm-1 were found to be the most active Raman modes of the low-energy Cdn clusters."
L. P. RAMÍREZ-RODRÍGUEZ,M. CORTEZ-VALADEZ,H. ARIZPE-CH AVEZ,J.-G. BOCARANDO-CHACON,R. RAMÍREZ-BON,S. VELUMANI,M. FLORES-ACOSTA 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.6
Colloidal nanoparticles were obtained by green synthesis, embedded in the Opuntia ¯cus-indicaplant extract. Optical measurements allowed us to detect two absorption bands centered in230 nm and 298 nm. Agglomerates of Pb nanoparticles have size in the range 2 – 8 nm. The ef-fective absorption cross section of spherical Pb nanoparticles was calculated by applying the Mietheory for colloidal systems and compared to optical absorption measurements of Pb nano-particles. The Raman spectrum of the samples after the reduction of Pb, shows a band at lowwavenumbers centered at 116 cm? 1 . Similar bands have been assigned to small Pb and Agclusters in other experimental results. Additionally, we used the density functional theory (DFT)as well as semi-empirical methods to assign this band to radial breathing modes of Pb metalnanoparticles.
Green Synthesis and Radial Breathing Modes in Ti Nanoparticles
R. Britto-Hurtado,M. CORTEZ-VALADEZ,Ramón A. B. Alvarez,P. Horta-Fraijo,J.-G. BOCARANDO-CHACON,R. Gamez-Corrales,A. Perez-Rodríguez,F. Martínez-Suarez,F. Rodríguez-Melgarejo,H. Arizpe-Chavez,M. FLORES 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5
This work presents the synthesis of metallic nanoparticles of titanium. The extract from the nopal (Opuntia ficus-indica) plant was used as the redactor agent. The results of transmission electronic microscopy (TEM) show that nanoparticles have a sphere-like shape with an approximate diameter of 1 – 4 nm. The presence of Ti in these particles was corroborated by energy dispersive X-ray spectroscopy (EDS). Optical properties were detected with the presence of absorption bands centered in 295 nm and 355 nm, similar to those reported in the literature. Two Raman bands centered at 359 cm-1 and 404 cm-1 were observed after the synthesis of titanium nanoparticles. Afterwards, structural and vibrational parameters of small clusters of Ti (Tin, n=3 – 13) were analyzed by the density functional theory (DFT) at the B3LYP level of approximation combined with the basis set LANL2DZ. Radial breathing modes (RBMs) were detected in the vibrational spectrum of each cluster, placed around 298 – 387 cm-1.