Content

The course will give an introduction to surface properties of relevance in nanoscience and nanotechnology. Emphasis will be given to the crystallographic structure, electronic states, thermodynamics and lattice and electron dynamics at the surface, and to gas surface interaction and catalytic reactions in the heterogeneous phase.

Frontal lectures (40 hours):

Surface crystallographic structure.

• The geometric surface plane and the two-dimensional surface lattice, its unit cell and symmetry properties, and surface relaxation and reconstruction.
• Direct and reciprocal lattices.
• Notation of surface structure:  low Miller index surfaces, vicinal surfaces, superlattices.
• Examples of the reconstruction of metal and semiconductor surfaces.
• Modification of the surface structure by physisorption and  chemisorption and crystal growth modes.
• Determination of the surface structure: diffraction methods vs microscopy.
• Low energy electron diffraction (LEED), and treatment of multiple scattering and dynamical LEED.
• Small angle scattering and high resolution in reciprocal space.
• Low energy electron microscopy and scanning probe microscopies (STM, AFM).
• Characterization of surface composition: Auger electron and X-Ray induced photoemission.

Surface Thermodynamics.

• Surface excess quantities.
• Surface energy, surface tension and work needed to create a surface.  
• Surface heat capacity.
• Surface energy and surface composition for alloys segregation.
• Island growth and ripening phenomena.

Surface Lattice Dynamics.

• The Surface phonon spectrum, bulk bands, and surface modes. T
• he Rayleigh wave.
• Surface phonon anomalies.
• Vibrational and thermal desorption spectroscopies.
• Surface Debye temperature.

Surface Electronic properties.

• The jellium model: internal potential and work function.
• The surface dipole layer and the face dependence of the work function.
• Surface band structure, and density of states at the surface and surface states.
• The image states and implication for photochemistry.
• Electronic excitations and  surface plasmons.

Graphene and other two dimensional crystals.

• Electronic properties and lattice dynamics in purely two dimensional systems.

Adsorption of gases and catalysis.

• Self assembled monolayers and artificial nanostructures.
• Physisorption vs Chemisorption.
• Gas surface interaction.
• Precursor states.
• Activated adsorption.
• Examples of catalytic reactions in the heterogeneous phase.  

Laboratory training (12 hours).

• Low energy electron diffraction.
• X ray photoemission and Auger electron spectroscopies.
• Scanning probe microscopies: STM, AFM.

Aims

Relevance of surfaces and interfaces in Nanoscience and Nanotechnology. The course will introduce: a) the surface excess quantities and thermodynamical properties of surfaces; b) the surface crystallographic structure with relaxation and reconstruction phenomena; c) the surface electronic ground state properties  and the surface states; d) the surface magnetic properties. Specific cases for semiconductor, oxide and insulator surfaces, graphene and other ultrathin films will be discussed with respect to dimensionality with extension towards one and zero dimensions, i.e atomic wires, surface steps and clusters. Excited states at surfaces will be treated: surface phonon spectra, surface electronic and magnetic excitations. Connections to plasmonics, Energy harvesting in solar cells and photoinduced chemistry will be stressed. Gas-Surface interaction, physisorption and chemisorption, dynamics of the interaction, adsorption, desorption, sticking and simple catalytic reactions will be discussed. Crystal growth, MBE, CVD, ablation techniques, nanosized films and clusters will be introduced as well as self-assembled monolayers, artificial nanostructures and surface functionalization. Experimental methods for surface characterization, like Scanning Probe Microscopies and Diffraction Methods, as well as  Surface Sensitive Electronic and Vibrational Spectroscopies will be introduced.

Pre-requiste

Introduction to solid state properties, principles of Quantum Mechanics

Recommended Books

• Gabor A. Somorjai and Yimin Li: Introduction to Surface Chemistry and Catalysis, second edition, Wiley.
• Teacher’s slides and other material will be provided to the students by the teacher.

Teaching Staff

Prof. Mario Rocca

Hours

Frontal lectures: 40 hours
Laboratory: 12 hours

Study hours for the students : 88h

Grading System

20% laboratory reports
80% final oral exam