The dipole moment of water. I. Dipole moments and hyperfine properties of H2O and HDO in the ground and excited vibrational states

Molecular beam electric resonance spectroscopy has been used to study H2O in its ground state and in each of its singly excited vibrational states. HDO was studied in its ground state and first excited O–H stretching state. Precise dipole moments have been obtained for a total of 14 rotational levels of six vibrational states. Centrifugal distortion corrections to the Stark coefficients were made and rotationless moments were calculated for each vibrational state. The magnitude of the H2O moment can be written μ(v1v2v3) =1.857 04+0.005 08(v1+ (1)/(2) ) −0.031 66(v2+ (1)/(2) ) +0.022 46(v3+ (1)/(2) ). Individual components of the HDO moment were obtained for the ground and excited states. Hyperfine properties were also determined for each of the vibrational states studied. In the following paper, the dipole moments are combined with infrared transition moments to obtain an improved dipole moment function for water.