Symmetry of theHCenter in KCl and KBr

$H$ centers were produced in KCl and KBr by x-irradiation at temperatures near liquid helium. The symmetry of these centers was determined by observing the dichroism produced in the absorption band after bleaching with polarized $H$-band light. It was found that the optical dipole moment of the $H$ center is parallel to $〈110〉$. The polarized bleaching light tends to reorient the $H$ centers as well as to bleach them. The oscillator strength of the $H$ center was found to be greater than about 0.3 that of the $F$ center in KCl and greater than about 0.5 that of the $F$ center in KBr.