The Production and Measurement of Anisotropy Using Photons
The alignment and orientation of a collision fragment can be determined by monitoring the polarized fluorescence emitted by a specific fragment state. Another way to determine fragment multipole moments is to observe the polarization of laser-induced fluorescence. The present paper reviews the relationship between the desired multipole moments and the intensity of laser-induced fluorescence, as derived from a viewpoint close to that of Fano and Macek. Time-resolved quantum beats in the fluorescence intensity have an amplitude which can often be directly expressed in terms of the fragment alignment and orientation. This relationship can be used to extract these moments or to correct for depolarization effects in time-unresolved experiments. Propensity rules for the angular distribution and the alignment of photofragments are discussed with reference both to examples and counterexamples. The photoelectron angular distribution and ionic alignment, generated by the simultaneous photoionization of helium accompanied by excitation of the hydrogenic ion, are analyzed with reference to predictions based on the hyperspherical potential curves of doubly-excited helium and are compared with recent experimental observations.
KeywordsAngular Momentum Asymmetry Parameter Multipole Moment Partial Cross Section Angular Momentum Operator
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- 1.K. Blum, Density Matrix Theory and Applications, (Plenum, New York, 1981), 217 pp.Google Scholar
- 3.U. Fano and G. Racah, Irreducible Tensorial Sets, (Academic, New York, 1959).Google Scholar
- 21.R. N. Zare et al., unpublished.Google Scholar
- 23.L. Kim and C. H. Greene, Phys. Rev. A 36, (November 1987).Google Scholar
- 26.M. J. Seaton, Proc. Phys. Soc. Lond. 77, 14 (1961).Google Scholar
- 27.H. R. Sadeghpour and C. H. Greene, to be published.Google Scholar
- 31.U. Fano and C. D. Lin, Atomic Physics 4, (Plenum, New York, 1975), p. 47.Google Scholar