Microwave optical double resonance was used to determine the electric dipol
e moment components along the axes of inertia of the HCF molecule. The valu
es are mu(a) = 0.043(5) D, and mu(b) = 1.402(6) D. Some of the rotational a
nd centrifugal distortion constants, previously determined from Doppler lim
ited optical spectra, were obtained with improved accuracy. (C) 2000 Elsevi
er Science B.V. All rights reserved.