HYPERFINE STRUCTURES OF PENDULAR STATES I N ICL A-STATE AND X-STATE

When a polar molecule is in an intense electric field, the first rotat ional levels are trapped by the dipole field interaction and become pe ndular. We present here the first results of an experimental and theor etical study of the hyperfine structures of these states in the case o f ICl A - X transition. We show that the hyperfine structure is the ke y for an unambiguous assignment of the observed lines. We thus prove t hat the dipole moments of the A and X states have the same sign, a res ult in contradiction with previous works but in good agreement with si mple quantum chemistry arguments.