Sumários
T26 - Experimental techniques for characterization of nano-systems
27 Maio 2024, 17:30 • Maria Margarida Cruz
The diffraction technique and accessible lengths. Low angle diffraction: operating principle, equipment and results.
Scanning probe microscopy - tunnel effect microscope, atomic force microscope and near-field optical microscope: working principle, equipment and results
Transmission electron microscopy and scanning electron microscopy: operating principle, equipment and results.
T25 - Experimental techniques for nano-systems preparation
27 Maio 2024, 15:00 • Maria Margarida Cruz
Top-down and bottom-up approach in the preparation of nanostructures.
Top-down - Machination. Types of micro-machining, their characteristics, limitations and systems in which they are applicable.
Lithography: description of the process. Types of lithography and their characteristics. Limitations.
"Bottom-up" - Preparation of films by chemical deposition (CVD). Some examples of chemical deposition techniques: thermal CVD, LACVD and MOCVD. Preparation of films by physical deposition. Some examples of physical deposition techniques: sputtering and electron beam evaporation. Colloidal synthesis.
Molecular manipulation using nano-indentation or nanolithography.
T24 - Optical properties of nanoparticles
20 Maio 2024, 17:30 • Maria Margarida Cruz
Optical properties - general approach. Optical properties of metals. Plasma frequency. Dielectric constant as a function of frequency. Dielectric constant of metallic nanoparticles. Clausius-Mossotti relationship. Surface plasmon. Dependence of the surface plasmon frequency on the dielectric constant. Metallic nanoparticles with diameters less than 20 nm. Quantum effects: redshift and resonance broadening.
Optical properties of semiconductors.Direct and indirect gap. Excitons. Optical properties of semiconductor nanoparticles. Exciton binding energy versus confinement. Semiconductor laser. Applications of nanoparticles.
T23 - Electronic properties
20 Maio 2024, 15:00 • Maria Margarida Cruz