Università degli Studi di Perugia

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Study-unit Code
Fisica della materia
Fernando Pirani
  • Fernando Pirani - Didattica Ufficiale
  • 42 ore - Didattica Ufficiale - Fernando Pirani
Course Regulation
Coorte 2018
Learning activities
Attività formative affini o integrative
Type of study-unit
Opzionale (Optional)
Type of learning activities
Attività formativa monodisciplinare
Language of instruction
Atoms in external fields. Hyperfine structure. State selection. Interaction potential. Atomic and molecular beams and experimental techniques. Collisions in classical mechanics. Cross sections. Semi-classical treatment. Quantum mechanical effects in collisions. Collision between identical particles. Polarized beams.
Reference texts
Lecture Notes provided by the Professor.
Educational objectives
The students that havefollowed the course
1) know the behavior of atoms in external magnetic and electric fields;
2) are able to describe the change in the electronic and nuclear angular momenta coupling as a function of the applied field intensity;
3) know the molecular beams technique and its extensive applications in the Atomic Physics field;
4) know the methodology adopted to realize, under high resolution conditions, collisional experiments between atoms and/or molecules addressed to the measure quantum mechanical interference effects in the scattering, which provide detailed information both on the collision dynamics and on the intermolecular forces involved;
5) know the differences between identical and different particle collisions;
6) know the general aspects of the vacuum technology and its applications in several fields.
In order to understand and to properly address the subjects presented and developed in the course, the student should know some basic principles of the quantum mechanics i. Such knowledge is useful to fully appreciate all the applications presented.
Teaching methods
-lectures on all subjects discussed in the course;
-at the beginning of any lecture it will be summarized the main arguments presented in the previously;
-illustrative exercises often are presented solved and discussed during the lectures;
-the last two/three lectures will be focused on the presentation and use of the vacuum technology.
Other information
No further information
Learning verification modality
The exam involves only a final oral test, consisting in a general a critical discussion on the topics presented and developed in detail during the course. The test aims at assuring the level of knowledge and the synthesis capacity achieved by the student, including its ability to use property of language and its capability to connect the different topics by using some basic principles. The duration of the exam is that necessary for obtaining the above check.
Extended program
General introduction to the subjects of the course: fine structure levels and the Lande’ factor.
The atom in an external field: the Zeeman and the Paschen Back effect in a magnetic field; the Stark effect in an electric field; coupling and decoupling of electronic angular moments in an external magnetic field.
Hyperfine structure in the atomic levels: nuclear spin and coupling between angular electronic and nuclear moments.
State selection with inhomogeneous magnetic fields: the Stern Gerlach experiment; the general features of Rabi and Rabi- Millan- Zacharias magnetic selectors; transmission and deflection method.
Behavior of atoms with hyperfine structure in an external magnetic field: complete treatment of the case concerning j=1/2 and any I; the Zeeman energies and the magnetic moments as a function of the strength of the applied magnetic field; limiting cases of angular momentum couplings.
Nature and properties of the intermolecular interaction potential: closed shell and anisotropic systems; atomic angular momentum decoupling in interatomic or intermolecular electric fields: adiabatic interaction potentials and correlation diagrams between atomic and molecular states.
Introduction to the experimental techniques for the investigation of collisional properties: production and control of the vacuum conditions, production and detection in gas phase of atomic and molecular beams.
Atomic and molecular beams: effusive beams and velocity distribution; supersonic beams and thermodynamic of the expansion process, the Mach number, the flow velocity and velocity distribution functions; seeded beams and their applications; relaxation a alignment effects of angular moments during the formation of seeded beams
Some relevant uses of beams: deceleration and confinement of atoms by the atomic and laser beams.
Collision in classical mechanics : laboratory and center of mass systems; the Newton diagrams; collisions and experimental observables; differential and total cross sections; classical mechanics treatment of the collision process by central field; relation between interaction potential and deflection angle.
Cross sections: cross sections in classical mechanics and singularities in their behavior; the collisional process in quantum mechanics; partial waves, role and properties of the phase shift of each wave.
Semi-classical treatment of the collisional process: relation between phase shift and trajectory ; the phase shift defined according to various approximations (Jeffreys, Wentzel, Kramers, Brillouin (JWKB) and Jeffreys, Born (JB)); cross section definition in the semi-classical approximation.
Nature and properties of quantum interference effects in the collision: diffraction, rainbow and glory phenomena and their dependence on the interaction potential; choice of the proper experimental conditions to measure quantum interference effects in the collisions: examples and discussion.
Collision between identical particles; restrictions imposed by the involved symmetry and symmetry oscillations; resonance effects and orbiting phenomenon.
Collisions by anisotropic potential: approximated schemes for the treatment, examples and discussion;
importance of using polarized atomic and molecular beams to study cross section properties and collision dynamics by anisotropic potential; parallelism between molecular rotation and collision.
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