A. Durand et al., HYPERFINE-STRUCTURE OF PENDULAR STATES AND THE SIGN OF THE DIPOLE-MOMENT OF ICI-A-STATE, The Journal of chemical physics, 101(5), 1994, pp. 3514-3519
Since a first study by Cummings and Klemperer [J. Chem. Phys. 60, 2035
(1974)] and further works by Friedrich and Herschbach, the dipole mom
ents of the X and A states of ICI are considered to have opposite sign
s. We have performed a high resolution study of the Stark effect of th
e A -X transition near the 21-0 bandhead, and we have made a complete
theoretical simulation of the spectrum, taking into account the hyperf
ine structure which is important. The comparison of the experimental s
pectrum with the simulation clearly prove that the dipole moments of t
he A and X state have the same sign. This result is in agreement with
simple electronegativity arguments.