Hanle effect in the solar Ba II D2 line: a diagnostic tool for   chromospheric weak magnetic fields
  The physics of the solar chromosphere depends in a crucial way on its magnetic structure. However there are presently very few direct magnetic field diagnostics available for this region. Here we investigate the diagnostic potential of the Hanle effect on the Ba II D2 line resonance polarization for the determination of weak chromospheric turbulent magnetic fields...... 
M. Faurobert, M. Derouich, V. Bommier, J. Arnaud