Electric Field Studies of the X Band Microwave Transitions in D2O

Abstract

Measurements of the zero field absorption lines and of the Stark splittings in D2O are reported for the 313 ← 220 and the 441 ← 532 transitions which are at frequencies near 10.9 GHz. Calculations of the hyperfine interactions using recent data describe well the absorption profiles of the zero field lines and are the basis for choosing the extrapolated zero field frequencies for the Stark frequency shifts. The dependence of the shifts on the square of the field strength is recalculated using recent data and compared with the experimental results. The dependence of the Stark shift on the fourth power of the field strength is also measured. The value of the dipole moment of D2O is found to be 1.857 ± 0.003 D for the 3 ← 2 transition and 1.884 ± 0.006 D for the 4 ← 5 transition, which indicates that there is a small dependence of the dipole moment on the rotational state for this molecule. The dependence is found to be greater than that reported previously.