Resonance fluorescence theory

Resonance coupling, Fe—S dimers, 38 446-451 Resonance delocalization, 38 426 Resonance effects, of astatophenols, 31 66 Resonance fluorescence, 46 156 nuclear, 6 438-445 theory of, 6 433 38... 

Case, D.A., McClelland, G.M. and Herschbach, D.R. (1978). Angular momentum polarization in molecular collisions Classical and quantum theory for measurements using resonance fluorescence. Mol. Phys., 35, 541-573. 

Corney, A. and Series, G.W. (1964). Theory of resonance fluorescence excited by modulated or pulsed light, Proc. Phys. Soc., 83, 207-216. 

Luh, W.T., Sando, K.M., Lyyra, A.M., and Stwalley, W.C., Free-bound-free resonance fluorescence in the K2 yellow diffuse band theory and experiment, Chem. Phys. Lett., 144, 221, 1988. 

The Hanle effect and the theory of resonance fluorescence experiments... 

This chapter opens with an account of resonance fluorescence and its depolarization by external magnetic fields, a phenomenon now knovm as the Hanle effect. Experiments of this type in mercury vapour are described and we develop a classical theory to explain the shape of the observed signals. This is followed by a discussion of the applications of this technique to the accurate measurement of atomic lifetimes. For the sake of simplicity the effects of interatomic collisions and of trapping or reabsorption of resonance radiation in these experiments are not considered... 

Next we proceed to develop the theory o resonance fluorescence experiments using the ensemble density matrix to describe the system of atoms. The important concepts of optical and radio-frequency coherence and of the interference of atomic states are discussed in detail. As an illustration of this theory general expressions describing the Hanle effect experiments are obtained. These are evaluated in detail for the frequently employed example of atoms whose angular momentum quantum numbers in the ground and excited levels are J =0 and Jg=l respectively. Finally resonance fluorescence experiments using pulsed or modulated excitation are described. 

The theory of resonance fluorescence experiments therefore reduces to a study of the solutions of the Liouville equation for appropriate forms of the Hamiltonian operator 30. 

Introduction and experimental techniques. In previous sections we drew attention to the fact that, in both the classical and quantum theories, expressions derived for the intensity of resonance fluorescence from atoms subjected to an external magnetic field, equations (15,3) and (15.23) respectively, contain terms which may lead to a modulation of the intensity at the Larmor frequency or its second harmonic. This radio-frequency modulation has been observed in several different kinds of experiment, the simplest of which makes use of pulsed excitation and time-resolved detection of the fluorescent light. 

Introduction and experimental technique. The classical theory of resonance fluorescence, in which the atoms are treated as dipole oscillators processing at the Larmor frequency, leads one to predict that interesting effects will also occur if the atoms are excited by light whose intensity is periodically modulated. As the external magnetic field is varied in these experiments a point is reached at which the Larmor frequency, equals the angu-... 

Theory of resonance fluorescence excited by modulated light. Theoretical expressions for the intensity of light observed in resonance fluorescence experiments using modulated excitation can be obtained by a simple extension of equation (15.41). We now assume that the energy density of the incident radiation, U((o,t), is amplitude modulated at... 

Comment on collisional depolarization studies. The resonance fluorescence experiments described above have served to stimulate and test the development of recent sophisticated theories of collision broadening. However, the hope that new information on interatomic forces would be obtained by these experiments has not been realized. This is largely because the observed broadening is the mean effect of collisions averaged over all possible relative orientations and over the thermal velocity distribution of the ensemble. It may be that in the future more detailed information on the interatomic potentials could be obtained by combining tunable dye laser excitation and atomic beam scattering techniques. 

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