To attend the course in the most profitable manner, general knowledge of fundamental aspects of structure of matter is recommended.

The program of the course is comprised of the following topics:

PART I: Phenomenology of surfaces and interfaces

1. Introduction to the course. Introduction to surfaces and interfaces. Surface/volume ratio. Microscopic interpretation of intermolecular forces. Interaction energy between ions, frozen and mobile permanent dipoles. Keesom energy.
2. Interaction energy with induced dipoles: Debye induction energy, London dispersive energy. Frequency dependence of atomic polarizability. Ionization energy. Van der Waals energy.
3. Additivity of Van der Waals interaction. VdW forces between macroscopic bodies: adsorption, adhesion, cohesion. Hamaker constant. Liquid surfaces. Interfacial thickness. Surface free energy and surface energy. Surface tension. Thermodynamics of interfaces in equilibrium: Gibbs theory. Definition of interface and Gibbs dividing plane. Interfacial excess.
4. Thermodynamic potentials at the interface. Thermodynamic definition of surface tension. Euler relation and Gibbs-Duhem relation. Surface tension and interfacial excess. Mixing entropy and mixing chemical potential. Surface activity: case of ionic, apolar, and amphiphilic solutes. Colloidal aggregates. Critical micellar concentration. Thermodynamics of colloidal aggregation.
5. Pressure difference across a curved surface: Young-Laplace equation. Vapor pressure at a curved surface: Kelvin equation. Supersaturation pressure. Theory of homogeneous nucleation. Heterogeneous nucleation. Wetting. Wetting line and contact angle. Young equation. Cases of partial, complete, and no wetting. Capillarity phenomena. Thin film formation. Dewetting. Pseudo partial wetting and wetting layer. Thin film deposition: dip coating and spin coating.

PART II: Surface characterization techniques

6. Scanning probe microscopy. Beam vs local probes. Atomic force microscope. Working principle: typical setup. Piezoelectric scanners and raster scan. Constant height mode and constant force mode. Interaction steepness and atomic resolution. Cantilever force sensors. Optical lever deflection detection method. Static mode of operation: contact mode. Jump-in-contact and jump-off-contact points. Lateral force and local friction coefficient measurement. Bidirectional optical lever.
7. Dynamic modes of AFM. Problems arising in static mode: thermal noise. Response function of the cantilever as a simple harmonic oscillator. Tapping mode. Phase sensitive coherent detection and lock-in detection. Effect of conservative and dissipative interactions on resonance curve. Frequency-modulation mode. Piezoelectric resonant force sensors: quartz tuning fork.
8. Combined scanning probes. Auxiliary distance control. Electrostatic Force Microscopy. Dependence of electric force on distance and electric properties of dielectrics. Voltage-modulated force detection. Dielectric constant, surface charge and contact potential measurement. Kelvin probe method. Kelvin probe force microscopy.
9. Nanotribology. Friction at a contact point measured by AFM. Stick-slip model for dissipation by dynamical friction. Friction of atomic layers. Quartz crystal microbalance (QCM). Gravimetric and non-gravimetric QCM. Interfacial viscosity and slip time.

Butt, Graf, Kappl, Physics and Chemistry of Interfaces, Wiley, 2003

Lecture notes (avaliable, in Italian, on elearning website of Physics Department:

https://elearning.df.unipi.it/enrol/index.php?id=254

Additional material in English is available on the same website.

For students not attending the class, the form of the standard oral exam is compulsory.

Oral exam, or presentation, in seminar form, of a detailed study concerning one of the topics of the course.

https://elearning.df.unipi.it/enrol/index.php?id=254

The course is composed by at least 18 hours of class teaching and one visit to research laboratories where experiments of surface physics using scanning probe microscopy are performed.