Debye
Debye is a CGS unit (symbol D) named after Peter J.W.Debye, Dutch-American, a physicist and Nobel laureate in Chemistry. It is defined as 1 × 10–18 statcoulomb-centimetre. It was originally defined as the dipole moment resulting from two charges of opposite sign but an equal magnitude of 10–10 electrostatic unit (esu). You may refer to it under "units and conversions" for more details.
The value of 1 Debye is as follows:
1 D = 10–18 statC.cm
= 10–10 esu.A°
= (1/299,792,458) × 10–21 C.m
∼ 3.33564 × 10– 30 C.m
∼ 1.10048498 × 1023 qPlP
∼ 0.393430307 ea0
∼ 0.20819434 eA°
Ex:

The dipole moment of a diatomic molecule is equal to 0.82 D. If its bond length is 1.4 A°, calculate the fraction of the electronic charge existing on each atom in the molecule. [1 Debye = 10–18 esu cm]?

Sol:
μ = 0.82 D
= 0.82 × 10–18 esu cm
r = 1.4 A°
= 1.4 × 10– 18 cm [1 A° = 10– 18 cm]
Let the fraction of the electronic charge(q) be x. Now we know that
μ = x × r
x = 0.82 × 10– 18 esu cm / 1.48 × 10–8 cm
= 0.585 × 10–10 esu
we know that the electronic charge on isolated ion = 4.8 × 10– 10 esu.
Thus, since out of 4.8 × 10– 10 esu electronic charge existing on each atom = 0.58 × 10–10 esu,
out of 100 esu electronic charge existing on each atom = (0.585 × 10–10 esu / 4.8 × 10–10) × 100
= 12.2%(Answer)
The answer can also be found by using the relation: % of electronic charge existing on each atom
= (μ(esu cm) / r(cm) × (4.8 × 10– 10 esu)) × 100 %
= (0.82 × 10– 18 esu cm / ((1.4 × 10– 8 cm) × (4.8 × 10– 10 esu ))) × 100
= 12.2 %