ATOM-INTERFEROMETRIC DETERMINATION OF THE DC-STARK SHIFT OF THE MG-INTERCOMBINATION LINE

The dc-Stark shift of the magnesium 3s2(S-1(0))-3s3p(P-3(1)) line is m easured by subjecting both arms of an atom interferometer to a constan t electric field. In this interferometer based on Ramsey's method of s eparated oscillating fields each am is uniquely associated with either the upper or lower state of the intercombination transition, so that the Stark energy perturbation provides two different potentials in the two arms of the interferometer. The resulting relative phase shift co rresponds to a difference of - (8.0 +/- 1.0) kHz (kV/cm)-2 in the pola rizabilities of the S-1(0) and the P-3(1)(Absolute value of m = 1) sta tes, in agreement with a theoretical calculation.