The Buckingham (symbol: B) is a CGS unit of electric quadrupole, named in honour of the chemical physicist A. David Buckingham who was the first to measure a molecular quadrupole moment. It is defined as 1×10−26 statcoulomb-centimetre2. This is equivalent to 1 Debye-Ångström, where 1 Debye = 1×10−18 statcoulomb-centimetre is the cgs unit of molecular dipole moment and 1 Ångström = 1×10−8 cm.
One Buckingham corresponds to the quadrupole moment resulting from two opposing dipole moments but an equal magnitude of 1 Debye which are separated by a distance of 1 Angstrom, a typical bond length. This is analogous to the Debye unit for the dipole moment of two opposing charges of 1×10−10 statcoulomb separated by 1 Angstrom, and the name Buckingham for the unit was in fact suggested by Peter Debye in 1963 in honour of Buckingham.