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11 results on '"Vikatakavi A"'

3. Ultrafast Dynamics of Plasmon-Mediated Charge Transfer in Ag@CeO2 Studied by Free Electron Laser Time-Resolved X-ray Absorption Spectroscopy

Author

Federico Boscherini, Sergio D'Addato, Claudio Masciovecchio, Patrick O'Keeffe, Laura Foglia, Paola Luches, Jagadesh Kopula Kesavan, Stefano Nannarone, G. Kurdi, Daniele Catone, Stefano Turchini, Eleonora Spurio, Ivaylo Nikolov, Giovanni De Ninno, Avinash Vikatakavi, Emiliano Principi, R. Mincigrucci, Stefania Benedetti, Jacopo Stefano Pelli Cresi, Cresi J.S.P., Principi E., Spurio E., Catone D., O'Keeffe P., Turchini S., Benedetti S., Vikatakavi A., D'Addato S., Mincigrucci R., Foglia L., Kurdi G., Nikolov I.P., de Ninno G., Masciovecchio C., Nannarone S., Kesavan J.K., Boscherini F., and Luches P.

Subjects
CeO, time-resolved XAS, Materials science, Bioengineering, 02 engineering and technology, CeO2, FEL, plasmonic nanoparticles, ultrafast charge transfer, General Materials Science, Solar photocatalysis, Plasmon, X-ray absorption spectroscopy, Plasmonic nanoparticles, business.industry, Plasmonic nanoparticle, Mechanical Engineering, Wide-bandgap semiconductor, Free-electron laser, Charge (physics), General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Optoelectronics, 0210 nano-technology, business, Ultrashort pulse
Abstract

Expanding the activity of wide bandgap semiconductors from the UV into the visible range has become a central goal for their application in green solar photocatalysis. The hybrid plasmonic/semiconductor system, based on silver nanoparticles (Ag NPs) embedded in a film of CeO2, is an example of a functional material developed with this aim. In this work, we take advantage of the chemical sensitivity of free electron laser (FEL) time-resolved soft X-ray absorption spectroscopy (TRXAS) to investigate the electron transfer process from the Ag NPs to the CeO2 film generated by the NPs plasmonic resonance photoexcitation. Ultrafast changes (

Published
2021

6. Ultrafast Dynamics of Plasmon-Mediated Charge Transfer in Ag@CeO

Author

Jacopo Stefano, Pelli Cresi, Emiliano, Principi, Eleonora, Spurio, Daniele, Catone, Patrick, O'Keeffe, Stefano, Turchini, Stefania, Benedetti, Avinash, Vikatakavi, Sergio, D'Addato, Riccardo, Mincigrucci, Laura, Foglia, Gabor, Kurdi, Ivaylo P, Nikolov, Giovanni, De Ninno, Claudio, Masciovecchio, Stefano, Nannarone, Jagadesh, Kopula Kesavan, Federico, Boscherini, and Paola, Luches

Subjects
time-resolved XAS, FEL, Letter, plasmonic nanoparticles, CeO2, ultrafast charge transfer
Abstract

Expanding the activity of wide bandgap semiconductors from the UV into the visible range has become a central goal for their application in green solar photocatalysis. The hybrid plasmonic/semiconductor system, based on silver nanoparticles (Ag NPs) embedded in a film of CeO2, is an example of a functional material developed with this aim. In this work, we take advantage of the chemical sensitivity of free electron laser (FEL) time-resolved soft X-ray absorption spectroscopy (TRXAS) to investigate the electron transfer process from the Ag NPs to the CeO2 film generated by the NPs plasmonic resonance photoexcitation. Ultrafast changes (

Published
2021

7. Ultrafast Dynamics of Plasmon-Mediated Charge Transfer in Ag@CeO2Studied by Free Electron Laser Time-Resolved X-ray Absorption Spectroscopy

Author

Pelli Cresi, Jacopo Stefano, primary, Principi, Emiliano, additional, Spurio, Eleonora, additional, Catone, Daniele, additional, O’Keeffe, Patrick, additional, Turchini, Stefano, additional, Benedetti, Stefania, additional, Vikatakavi, Avinash, additional, D’Addato, Sergio, additional, Mincigrucci, Riccardo, additional, Foglia, Laura, additional, Kurdi, Gabor, additional, Nikolov, Ivaylo P., additional, De Ninno, Giovanni, additional, Masciovecchio, Claudio, additional, Nannarone, Stefano, additional, Kopula Kesavan, Jagadesh, additional, Boscherini, Federico, additional, and Luches, Paola, additional

Published
2021
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8. Physical Synthesis and Study of Ag@CaF 2 Core@Shell Nanoparticles: Morphology and Tuning of Optical Properties

Author

Maria Chiara Spadaro, Luca Pasquali, Avinash Vikatakavi, Sergio D'Addato, and Sergio Valeri

Subjects
X-ray photoelectron spectroscopy, Morphology (linguistics), Materials science, Ag nanoparticles, Scanning electron microscope, Core shell nanoparticles, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Chemical engineering, core–shell nanoparticles, optical reflectvity, scanning electron microscopy, surface plasmon resonance, Electronic, Physical synthesis, Optical and Magnetic Materials, Surface plasmon resonance, Ag nanoparticles core-shell nanoparticles optical reflectvity surface plasmon resonance scanning electron microscopy X-ray photoelectron spectroscopy
Abstract

Pre-formed Ag nanoparticles (NPs) and Ag@CaF2 core-shell NPs are physically synthesized using DC magnetron-based NP source and deposited on Si-SiOx wafers. The samples are prepared by co-depositing Ag nanoparticles and CaF2 produced by an evaporation source, or by sequential deposition method, i.e., by depositing in a sequence a CaF2 buffer layer, the Ag NPs generated by the NP source and a capping CaF2 layer. The supported films are characterized by Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Surface Differential Reflectivity (SDR). SEM shows that Ag NPs deposited directly on Si-SiOx tend to diffuse and to agglomerate, affecting the size distribution of the nanostructures. The presence of a CaF2 buffer layer between Ag and Si-SiOx limits this effect, while XPS reveals electrical charging, caused by the insulating nature of the CaF2 continuous film. The surface plasmon resonance behavior for different samples is analyzed using SDR with p-polarized light. There is a clear evidence of a blue shift in the plasmon excitation due to the presence of CaF2 on Si, which can represent a potential advantage for the technological applications in photovoltaics and optoelectronics.

Published
2019

10. Physical Synthesis and Study of Ag@CaF2 Core@Shell Nanoparticles: Morphology and Tuning of Optical Properties.

Author

D'Addato, Sergio, Vikatakavi, Avinash, Spadaro, Maria Chiara, Valeri, Sergio, and Pasquali, Luca

Subjects
*MAGNETRON sputtering, *OPTICAL properties, *SURFACE plasmon resonance, *X-ray photoelectron spectroscopy, *NANOPARTICLES, *SCANNING electron microscopy
Abstract

Pre‐formed Ag nanoparticles (NPs) and Ag@CaF2 core–shell NPs are physically synthesized using DC magnetron‐based NP source and deposited on Si‐SiOx wafers. The samples are prepared by co‐depositing Ag nanoparticles and CaF2 produced by an evaporation source, or by sequential deposition method, i.e., by depositing in a sequence a CaF2 buffer layer, the Ag NPs generated by the NP source and a capping CaF2 layer. The supported films are characterized by Scanning Electron Microscopy (SEM), X‐ray Photoelectron Spectroscopy (XPS), and Surface Differential Reflectivity (SDR). SEM shows that Ag NPs deposited directly on Si‐SiOx tend to diffuse and to agglomerate, affecting the size distribution of the nanostructures. The presence of a CaF2 buffer layer between Ag and Si‐SiOx limits this effect, while XPS reveals electrical charging, caused by the insulating nature of the CaF2 continuous film. The surface plasmon resonance behavior for different samples is analyzed using SDR with p‐polarized light. There is a clear evidence of a blue shift in the plasmon excitation due to the presence of CaF2 on Si, which can represent a potential advantage for the technological applications in photovoltaics and optoelectronics. [ABSTRACT FROM AUTHOR]

Published
2019
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11. Ultrafast Dynamics of Plasmon-Mediated Charge Transfer in Ag@CeO 2 Studied by Free Electron Laser Time-Resolved X-ray Absorption Spectroscopy.

Author

Pelli Cresi JS, Principi E, Spurio E, Catone D, O'Keeffe P, Turchini S, Benedetti S, Vikatakavi A, D'Addato S, Mincigrucci R, Foglia L, Kurdi G, Nikolov IP, De Ninno G, Masciovecchio C, Nannarone S, Kopula Kesavan J, Boscherini F, and Luches P

Abstract

Expanding the activity of wide bandgap semiconductors from the UV into the visible range has become a central goal for their application in green solar photocatalysis. The hybrid plasmonic/semiconductor system, based on silver nanoparticles (Ag NPs) embedded in a film of CeO 2 , is an example of a functional material developed with this aim. In this work, we take advantage of the chemical sensitivity of free electron laser (FEL) time-resolved soft X-ray absorption spectroscopy (TRXAS) to investigate the electron transfer process from the Ag NPs to the CeO 2 film generated by the NPs plasmonic resonance photoexcitation. Ultrafast changes (<200 fs) of the Ce N 4,5 absorption edge allowed us to conclude that the excited Ag NPs transfer electrons to the Ce atoms of the CeO 2 film through a highly efficient electron-based mechanism. These results demonstrate the potential of FEL-based TRXAS measurements for the characterization of energy transfer in novel hybrid plasmonic/semiconductor materials.

Published
2021
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