Influence of nuclear spin on angular distribution and polarization of photoelectrons: resonant two-photon ionization of Na

✍ Scribed by Michael P Strand; John Hansen; Ring-Ling Chien; R.Stephen Berry

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 456 KB
• Volume: 59
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(78)89079-4

✦ Synopsis

Resonant ionization of Na through its 3p levels by two pulsed lasers illustrates how coherent excrtatton of hyperfime leveIs affects the ang&r distributions of photoelectrons and of electron spin polarization. The effects appear as dependence of the distributions on the time interval between excitation and ionization pulses. Theoretical and experimental results are given for photoelectron distnbutions, and seveml microscopic parameters are determined. Tbeore.tical predictions are given for angle-and time-dependence of spin polarization. l-Iatroduction 23is report describes the infhrence of coherence in an excited state on angular properties of phGtoelectrons. fn particular, we examine -both theoretically and experimentally -the effect of coherence among hyperfine states on the angular distribution of photoelectrons from the resonant two-photon process Na(3s *S) + Na(3p *PIP) + Na+ f e, as excited by two linearly-polarized pulsed laser beams, and, as a theoretical prediction only, the angular dependence of electron spin polarization from ionization through Na(2FJn) -+ Na* f e by two circularly-polarized beams. The effects are observed by variation of the time inter& between the laser pulses. Atomic sodium excited to its "PsD level with the 4 ns pulse of a dye laser tuned to 58899 nm, enters a superposition of the hyperfiie states of this level. A second light pulse, from a N2-laser (337.1 nm), photoionizes the excited atoms. The theory outlined below shows that this angular distriiution depends on the degree of coherence among the hyperfine levels, and on the time interval between the exciting pulse and the ionizing pulse. The distribution also depends on the shapes and degrees of coherence of the light