Angular distributions of photoelectrons from excited valence1,3P1ostates of Ca, Sr, and Ba

Angular distributions are reported for energy-resolved electrons obtained by resonance-enhanced multiphoton ionization of alkaline-earth atoms through excited intermediate valence states. The angular distributions are measured as functions of the independently variable polarizations of the exciting and ionizing laser beams. This report treats the following states, resonantly formed and photoionized: Ca(4s4p) ${}_{}{}^1{}_{}{}^{}P_1^o{}_{}{}^{}$, Sr(5s5p) ${}_{}{}^1{}_{}{}^{}P_1^o{}_{}{}^{}$, Sr(5s5p) ${}_{}{}^3{}_{}{}^{}P_1^o{}_{}{}^{}$, Ba(6s6p) ${}_{}{}^1{}_{}{}^{}P_1^o{}_{}{}^{}$, and Ba(6s6p) ${}_{}{}^3{}_{}{}^{}P_1^o{}_{}{}^{}$. Systematic behavior in the resulting photoelectron angular distributions is explored. The effects of the hyperfine interaction are apparent.