Sign and direction of the dipole moment

Whereas calculated dipole moments are obtained as a vector, with a specified direction, experimentally obtained dipole moments typically do not specify direction and thus are obtained as a scalar. Thus, additional work is usually needed to obtain the direction. The answer can be provided in several different ways. 

One possibility is to use hybrid orbitals. For e ple, any s hybridization in the HCl bond will give the correct direction of the dipole moment, HCl [58], In a similar fashion, consideration of the possible resonance structures in a molecule and determination of the most important one (based on the electronegativities of the respective atoms) will give the correct direction. For example, in OT, H F is much more important than H F, thus giving the direction of the dipole moment as HF. 

Precise measurements of the effect of isotopic substitution on hyperfine Zeeman splitting effects [64] have provided the correct direction of the dipole moment for carbon monoxide, CO [65], deuterium iodide, DI [66], and carbonyl sulfide, OCS [67], 

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