Study-Unit Description

Study-Unit Description


TITLE Atomic Physics

LEVEL 03 - Years 2, 3, 4 in Modular Undergraduate Course



DESCRIPTION Atomic physics is a subject of fundamental importance, covering everything from the physics of chemical reactions, the workings of lasers, ultra-precise metrology, and cosmology. This study-unit will introduce the main concepts of atomic physics, starting from an exploration of the hydrogen atom and building up to a description of the effects of magnetic and electric fields on atomic spectra. The main principles behind lasers are also introduced, and a description of laser cooling of simple atoms given.

Study-unit Aims:

This unit aims to acquaint the student with several important aspects of atomic physics. It consists of:
(i) an exploration of both classical and quantum models of the hydrogen atom, and an extension to alkali atoms;
(ii) a description of the main features of atomic spectra;
(iii) a discussion of allowed and forbidden atomic transitions;
(iv) the effect of magnetic and electric fields on atomic spectra; and
(v) an understanding of the basic concepts behind lasers and laser cooling of simple atoms.

Learning Outcomes:

1. Knowledge & Understanding
By the end of the study-unit the student will be able to:

- list the three major spectroscopic divisions of an atomic spectrum and describe their origin;
- describe the Bohr model of the hydrogen atom;
- explain the various steps involved in deriving the quantum mechanical hydrogen wave-functions;
- list and describe the origin of the selection rules governing electric dipole transitions;
- describe the main broadening mechanisms affecting spectral features;
- explain the concept of the quantum defect as an effective picture for alkali atoms;
- explain why ordinary vector addition does not apply to atomic angular momenta;
- compare the L-S and jj coupling schemes;
- list Hund's rules;
- explain the importance of the Pauli exclusion principle and the exchange energy in the Helium spectrum;
- describe the quantum-mechanical origin of the spin-orbit coupling in alkali atoms;
- describe the origin of the Zeeman, Paschen-Beck, and Stark effects;
- list the main components of any laser;
- compare single- and multi-mode lasers, and explain the principles behind laser mode locking;
- list and describe at least two kinds of each of gas and solid-state lasers;
- describe how optical molasses and magneto-optical traps work;
- explain the physical origin of the Doppler and recoil limit temperatures;
- explain the concept of Bose-Einstein condensation.

2. Skills
By the end of the study-unit the student will be able to:

- calculate the allowed energies and orbital radii of a hydrogen atom in the Bohr model;
- use given values of quantum defects to calculate the wavelength of spectral features of alkali atoms;
- work out the ground-state terms and electronic configurations of the first few elements of the periodic table using Hund's rules;
- calculate the approximate value of the spin-orbit coupling for the hydrogen atom in the Bohr model;
- derive a formula for the spin-orbit energy shift under L-S coupling;
- calculate the number and properties of spectral features of an atom subjected to a magnetic field;
- derive the threshold condition for sustaining lasing action;
- derive the relationships linking the Einstein coefficients;
- use the four-level laser model to derive an expression for the population inversion;
- calculate the Doppler and recoil temperatures.

Main Text/s and any supplementary readings:


- W Demtröder, "Atoms, Molecules and Photons", Springer-Verlag
- H Haken and H C Wolf, "The Physics of Atoms and Quanta", Springer-Verlag


- C Foot, "Atomic Physics", Oxford University Press

ADDITIONAL NOTES Pre-Requisite Study-unit: PHY2140


Assessment Component/s Resit Availability Weighting
Worksheets SEM1 No 20%
Assignment SEM1 Yes 20%
Oral Examination SEM1 Yes 60%

LECTURER/S Andre Xuereb

The University makes every effort to ensure that the published Courses Plans, Programmes of Study and Study-Unit information are complete and up-to-date at the time of publication. The University reserves the right to make changes in case errors are detected after publication.
The availability of optional units may be subject to timetabling constraints.
Units not attracting a sufficient number of registrations may be withdrawn without notice.
It should be noted that all the information in the description above applies to study-units available during the academic year 2021/2. It may be subject to change in subsequent years.