Generation of dichroic h centres in KCl by polarized optical bleaching of interstitial atomic hydrogen

Upon optical bleaching of interstitial atomic hydrogen (H or U2 centres) with polarized light U and H centres (H and Cl ) are produced, the latter in an unbalanced distribution which is measured by optical absorption and ESR. Similar results are obtained for bleaching of U2 centres in a mixed configuration with one Br− as nearest neighbour (H (Br)). In the H centre formation Clo is ejected to form a Cl−2 crowdion only into those [110] directions which appear perpendicular to the [111] optical transition moment of the U2 charge transfer transition. It is concluded that H centres are formed in an excited π‐state.