Photoelectron angular distributions

Relativistic, multipole, and screening effects on photoelectron angular distributions are examined using the numerical partial-wave single-electron-transition code previously applied to total cross sections. We present data on the development of relativistic and higher-multipole corrections to the nonrelativistic dipole approximation, showing that these effects are not well described by such simple factors as $1+4\beta cos\theta$ and in fact persist to threshold in high-$Z$ elements. We trace the disappearance of screening effects on the distribution with increasing energy as screening becomes simply a multiplicative normalization effect on the total cross section, and so discuss ways to parametrize angular-distribution data. Finally, we compare theory with existing experiments, including a comprehensive comparison with all experiments at 100-eV energies and above.