Scattering polarization of hydrogen lines from electric-induced atomic alignment
R. Casini, R Manso Sainz
We consider a gas of hydrogen atoms illuminated by a broadband, unpolarized radiation with zero anisotropy. In the absence of external fields, the atomic J-levels are thus isotropically populated. While this condition persists in the presence of a magnetic field, we show instead that electric fields can induce the alignment of those levels. We also show that this electric alignment cannot occur in a two-term model of hydrogen (e.g., if only the Ly-alpha transition is excited), or if the level populations are distributed according to Boltzmann's law.
arXiv:0705.4133•Journal of Physics B Atomic Molecular and Optical Physics•Apr 7, 2008•1 citation